It sounds like you might be having trouble with WP-Juicebox (the Juicebox plugin for WordPress) and the Visual Composer plugin for WordPress but I can't be sure.
Could you please confirm if this is the case and also explain in detail what the problem is? Thank you.
Is the problem with the creation and/or management of galleries in the WordPress Dashboard or with the visual presentation of the galleries in the front-end of your site?
(Please note that WP-Juicebox does not work in conjunction with any other plugins. It is a standalone plugin which can be used to create a Juicebox gallery in a WordPress page or post. The embedding code is handled internally by the plugin.)

If the problem is with the gallery display, then please check your gallery's web page (using your browser's developer tools) to see if there is any custom CSS which might be interfering with the gallery.
Many WordPress plugins and themes use global CSS rules which might, for example, be applied to all <img> or <div> tags on a web page. If this is the case, then your Juicebox gallery may be inheriting these CSS rules and they may be affecting your gallery's layout or functionality.

Please also check these FAQs to see if any of them describe the problem you are facing and offer a solution.

If you are not using WP-Juicebox but are just trying to embed a Juicebox gallery into a WordPress page manually, then be sure to enter your gallery's embedding code as raw HTML (rather than plain text). Using the regular WordPress editor, you would enter the embedding code in 'Text' mode rather than 'Visual' mode.
I would recommend using the baseUrl method of embedding as documented here.
You can upload your gallery folder to anywhere on your web server as long as the two paths within the baseUrl embedding code (the path to the 'juicebox.js' file and the baseUrl itself, pointing towards the gallery folder) are correct.

If you continue to experience difficulties, then please post back with the URL to your gallery's web page (if the problem is in the front-end of your site) so that I can take a look at the problem for myself and hopefully help further.
If the problem is in the admin section of your site, then please describe what the problem is and provide a screenshot, if possible, so that I can see what you are seeing.

Hopefully my notes above will help.

It is not possible to save new default values for configuration options in JuiceboxBuilder-Pro but you can save a custom combination of configuration options as a 'Preset' file ('Presets -> Save Preset...' from the drop down menu at the top).

When you next edit or create a gallery, you can apply this 'Preset' file to your gallery (to set all your custom configuration options at once and save you from having to set them all individually) via 'Presets -> Load Preset...'.

You can have as many 'Preset' files as you like (each holding different configuration option values).
Please see the 'Presets' section of the JuiceboxBuilder-Pro User Guide for more information.

(You can save new default values only for image sizes. On the 'Images' tab, you can click the 'Change Sizes...' button in the 'Image Size' control panel to set image dimensions and, if you click 'Save Defaults', then the current values will become default values for new galleries.)

No. WP-Juicebox is hosted only on our own web site. You can download the plugin from its support page here.
Instructions for installing and using the plugin can be found on the same page.

Yes. The pugin's 'readme.txt' file has a 'Tested up to: 4.7.2' tag but this is only because 4.7.2 was the most recent version of WordPress when the current version of the plugin was released. The plugin has been tested with (and is compatible with) WordPress 4.7.3.

You can upgrade a Lite gallery to Pro by either of the following methods:
(1) Open the Lite gallery in JuiceboxBuilder-Pro(click the 'Open Gallery...' button on the 'Start' tab and select the gallery folder) and re-save it on the 'Publish' tab.
... or:
(2) Replace your Lite gallery's 'jbcore' folder with the Pro version from the Juicebox-Pro download zip file ('juicebox_pro_1.5.1/web/jbcore').

All image titles and captions will be preserved using either of the methods above.
If you open your Lite gallery with JuiceboxBuilder-Pro, you can change any of the configuration options (such as the Back Button options) on the 'Customization' tab before re-saving your gallery.

Deselect the Show Open Button checkbox in JuiceboxBuilder-Pro's 'Customize -> Lite' section.

You would use the embedding code to insert your gallery into an existing web page alongside other content.
All galleries need to be embedded into a web page. The 'index.html' files created by JuiceboxBuilder use the embedding code to embed the galleries into web pages of their own (with no other content on the web pages). If you open one of your gallery's 'index.html' pages in a plain text editor, you'll see the embedding code there.

You can save a combination of configuration options as a 'Preset' ('Presets -> Save Preset...' from the drop down menu at the top). You can then load this preset (to set all your custom configuration options at once and save you from having to set them all individually) via 'Presets -> Load Preset...'.
Please see the 'Presets' section of the JuiceboxBuilder-Pro User Guide for more information.

The 'juicebox.js' file must be loaded on its own from within the gallery's 'jbcore' folder. Juicebox looks for a separate <script> tag on the embedding page loading the 'juicebox.js' file in order to determine the location of the 'jbcore' folder (in turn, to load other resource files from within the 'jbcore' folder).

It is not possible to combine the code from the 'juicebox.js' file along with other JavaScript files in one larger combined file. (It sounds like this is what 'Combine Js Plus' does.) As you have discovered, this will break Juicebox galleries.

Yes. The gallery font face can be changed via the galleryFontFace configuration option (Pro only). A short description of this option can be found in the General section of the Config Options page.
To change font sizes (and to use other styling such as bold), you can use HTML formatting in individual captions or CSS (to change the font size of all captions globally). Please see this forum post for details.

Yes. You can choose which buttons you'd like to display on your gallery's Button Bar. Each button can be displayed (or hidden) individually. Please see the Button Bar section for details.

Yes. Captions are still displayed in fullscreen mode. (Juicebox-Pro uses the same captionPosition value for both normal and fullscreen modes.) Try viewing this demo gallery and clinking the expand button to go fullscreen and you'll still see the captions.

No.

Yes. You can choose whatever audio track you like (subject to copyright). Please see the Adding Audio support section for details.

For reference, a list of all configuration options can be found here and the home page for our online support is here.

You're welcome.

Unfortunately, it is not possible to change the Email Button's body text. The text is buried deep within the 'juicebox.js' file which is obfuscated and cannot be modified.
We plan to make it possible for users to translate "Regarding image" and "in gallery" (via the languageList configuration option) in the next version of Juicebox-Pro but, as far as I am aware, there are no plans to allow the entire text to be substituted.

The best I can suggest at the moment is that you either:
(1) Suggest your idea (to be able to replace the Email Button's body text) for a future version in the Feature Requests forum thread. This keeps all the ideas together and ensures that they are not overlooked by the developers.
... or:
(2) Override the Email Button and create your own 'mailto' link (with your own custom body text) as suggested in this forum post. (Please note that modifications such as this which override Juicebox's own built-in functionality are not officially supported and while you are free to try them, you might find that you encounter unforeseen knock-on problems which might need to be tackled along the way.)

1. When I view your gallery on my own iOS mobile device, I see the Splash Page (rather than a thumbnail page showing a grid of thumbnails). If you have changed your gallery's configuration options recently, try clearing your browser's cache before reloading your gallery's web page to ensure that your browser is fetching the latest gallery files from your server (instead of perhaps using older cached versions).

2. After a gallery has been expanded from the Splash Page, the user can click the Expand/Close Button (on the gallery's Button Bar) to return to the embedding page. Just be sure to set showExpandButton="TRUE" (in JuiceboxBuilder-Pro's 'Customize -> Lite' section). You'll also need to make sure that you do not set buttonBarPosition="NONE" ('Customize -> Button Bar'). You can see the Expand/Close button in the top right corner after expanding this demo gallery from its Splash Page.

3. It can sometimes be difficult to scroll past an embedded gallery. If you initiate a scrolling swipe on a gallery, then unless you are very precise with your up or down motion, the gesture may be interpreted by Juicebox as the start of a navigation swipe (to go 'previous' or 'next' on a thumbnail page or a main image). This will not be a problem when the Splash Page is displayed. It may only be a problem when the gallery is embedded without the Splash Page (screenMode="LARGE" or showSplashPage="NEVER").

4. captionPosition is a Large Screen Mode configuration option only. (This is noted in the description for captionPosition in the Caption Options section of the Config Options page). In Small Screen Mode (on mobile devices), captionPosition is always set to OVERLAY (where the caption area sits at the foot of the gallery and spans the width of the gallery). This gives the captions as much room as possible on mobile devices.

I notice that your gallery currently uses Juicebox-Pro v1.4.3.2. You might like to try upgrading your gallery to the latest version (v1.5.0) as many bugs have been fixed (and new features introduced) since v1.4.3.2. (Depending on the mobile device you are using to view your galleries, this might help with your first query above.) For reference, a list of changes between versions can be found on the Version History page. Full instructions on how to download the current version and upgrade existing galleries can be found on the Upgrading Juicebox support page.

No problem.
I have replied to your caption query here.

If you are using JuiceboxBuilder-Pro to create or edit your gallery, then you can clear all image titles at once by going to 'Images -> Titles -> Use None' from the drop-down menu at the top. (You can do likewise for the image captions via 'Images -> Captions -> Use None'.)
Then just re-save your gallery on the 'Publish' tab afterwards.

If you want to prevent the entire caption area from being displayed in the gallery, then set captionPosition="NONE" (in JuiceboxBuilder-Pro's 'Customize -> Caption' section).