If you are using JuiceboxBuilder-Pro (the standalone desktop application to create and edit galleries which comes with Juicebox-Pro), click a thumbnail on the images tab and you'll see individual input boxes (below the thumbnails) where you can enter an image title and caption. You can enter a different title and caption for each image.

If you are using the Lightroom plugin, perhaps the easiest way to enter individual image titles and captions would be add the text as metadata and then have the plugin extract it for use in the gallery. This can all be done within Lightroom.
In the Library section, select an image and scroll down to the Metadata section on the right. Now enter an image title in the Title box and a caption in the Caption box.
When you then go to the Web section and select Juicebox-Pro as the Layout Style, the plugin will automatically use the Title and Caption by default for each image in the gallery (although you can extract whatever metadata you like for use as the image titles and captions by editing the Title and Caption templates in the plugin's Image Info section.)

You can leave the metadata in place for just the duration of creating the gallery or you can save it to your source images.
If you do this, the image titles and captions will be embedded within the images themselves and can be extracted for use in future galleries (using either JuiceboxBuilder-Pro or the Lightroom plugin).

I am glad that you've been able to resolve your problem.
Thank you for letting me know and for sharing your workflow.
Hopefully it will help other users who are experiencing a similar issue.

What you are describing is the Splash Page.
The Splash Page is a placeholder for the gallery which is displayed by default on small screen devices when the gallery is embedded in a page alongside other content (rather than displayed on a page of its own with dimensions of 100% x 100%, filling the browser window).
When the user clicks/taps the Splash Page, the gallery is expanded to fill the user's browser window.
For more information about the Splash Page and how Juicebox adapts to different devices and screen sizes, please see here.

You can choose to not use the Splash Page by setting showSplashPage="NEVER".
Alternatively, you can force the gallery to be displayed in Large Screen Mode (which, by default, does not use the Splash Page) on all devices and in all browsers by setting screenMode="LARGE".

If you choose to continue to use the Splash Page, you can customize it using the Splash Page configuration options.

A browser's developer tools can be very useful but they are not always the most accurate way to emulate a mobile device and determine how a gallery will look on such a device. (Just something to bear in mind when testing your page's layout.)

Please see this FAQ:
My Juicebox gallery shows too much space above or below the main image, how do I fix this?

Please see this note regarding Using Percentage Heights.

When setting a percentage height, make sure that all parent containers of your gallery have heights set via CSS. Otherwise, Juicebox may not be able to determine what its actual height should be. For example, if you set a gallery height of 100%, Juicebox needs to know what its height should be 100% of. In a CMS environment (such as Drupal) where you may have little or no control over the containers that the gallery is nested within, it might be wise to use a fixed pixel height (such as '600px') instead of a percentage to avoid problems that can arise when using a percentage.

If your current theme does not already so so, you could try scaling your web page for mobile devices but adding the following tag to the head section of your web page. This might help.

<meta name="viewport" id="jb-viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1, maximum-scale=1, user-scalable=0" />

Set showAutoPlayButton="TRUE" and the AutoPlay Button will de displayed in the Button Bar and the user can click/tap this to toggle AutoPlay on and off.

I hope this information helps.

Please note that the Juicebox module for Drupal is an unofficial plugin which was not written by ourselves (but is well supported by its author in the Drupal forum). This is noted on the module's support page:

Upgrading the Drupal module to Juicebox-Pro does not change the module's interface.
There are no individual controls for each Pro configuration option. Instead, you can add Pro configuration options as text (for example, autoPlayOnLoad="TRUE") into the 'Juicebox Library - Pro / Manual Config' section of your Drupal Dashboard ('Home -> Administration -> Structure -> Content types -> Article -> Manage Display -> Juicebox settings').
Here is a Drupal forum post with the author's thoughts on adding further options to the module's interface.

This sounds like there may be a CSS conflict between your current theme and the your Juicebox gallery. Some CSS rules from your theme might be overriding the gallery's own CSS rules and adversely affecting the gallery's layout. If your theme uses global CSS rules which, for example, apply to all <div> or <img> tags on your web page, then they will also apply to these elements within the gallery. It is not possible to isolate a Juicebox gallery (or any other HTML element) from global CSS rules and the gallery will have no option but to inherit them. The best solution would be to apply CSS rules to only those elements on your web page that require them through use of CSS selectors (classes and ids). However, this might be difficult with a theme that you did not write yourself.
You might like to at least test this theory by using a different theme (at least for testing purposes) to see if it makes a difference.

You can also use your browser's developer tools (usually accessible via F12) to investigate which CSS rules are being applied to which HTML elements on your web page.
Please see this forum post for links to pages which might help if using a browser's developer tools.

Watermarking is a feature of JuiceboxBuilder-Pro (the desktop application which comes with Juicebox-Pro) only. Please see the Adding Watermarks support section for details.
Images are watermarked at the time the gallery is built by the application (at the same time the images are resized for the gallery). The watermarks are not added at the time the gallery is displayed so there are no watermark options which can achieve this.
You could perhaps use JuiceboxBuilder-Pro to watermark your images and then upload the watermarked images for use in your Juicebox gallery within Drupal.

Please see the Adding Audio support section for details.
You would need to point towards MP3 and OGG versions of an audio track using the audioUrlMp3 and audioUrlOgg Pro configuration options.
You could also set playAudioOnLoad="TRUE" (to automatically start the audio track playing when the gallery is initially loaded) and/or showAudioButton="TRUE" (to display the Audio Button on the Button Bar and allow visitors to your web site to toggle the audio on and off).

I hope these notes help to clarify things.

Try running your gallery page's URL through the Facebook Sharing Debugger: https://developers.facebook.com/tools/debug/
You could try their Open Graph Object Debugger, too: https://developers.facebook.com/tools/debug/og/object

This should refresh Facebook's cache of your web page, including Open Graph tags (although it may not be instant).

Here are a few other suggestions I've found on the web which may or may not help (but might be worth trying).

(1) Try placing your og:image tag before all others on your web page.

(2) Try using og:image:type, og:image:width and og:image:height Open Graph tags in addition to your og:image tag. For your image, try the following:

<meta property="og:image:type" content="image/jpeg" />
<meta property="og:image:width" content="1024" />
<meta property="og:image:height" content="730" />

(3) Try renaming the image you use for your og:image (and the corresponding og:image value itself) so that Facebook has to fetch the 'new' image.

Hopefully one of these suggestions will help.

The following should work (as long as the $Url variable has already been defined earlier in the page).

baseUrl: "<?php echo $Url; ?>",

You might also need to use the $Url variable in the path to the 'juicebox.js' file, e.g.:

<script src="<?php echo $Url; ?>/jbcore/juicebox.js"></script>

The code above assumes that your $Url variable does not end with a slash. You can adjust the code if necessary.

Suggestions from user222 in this forum thread: https://juicebox.net/forum/viewtopic.php?id=2171

I'm glad you've got things working.
Thank you for letting me know.

The og:image entry must be an absolute URL in the form http://www.example.com/gallery/images/image001.jpg
A relative path will not work.

You can either:

(1) Edit your gallery's 'index.html' page in a plain text editor and change:

<meta property="og:image" content="/images/20120317_126-Edit.jpg" />

... to:

<meta property="og:image" content="http://www.judophoto.com.au/judo/kidsjudo/images/20120317_126-Edit.jpg" />

... or:

(2) Rebuild your gallery with the Lightroom plugin and enter your gallery directory's URL (http://www.judophoto.com.au/judo/kidsjudo) as the 'Share Url' in the 'Sharing' section.
The plugin will use this as the first part of the path for the og:image entry (before completing the path to the first image in the gallery).

I hope so, too.

You're welcome!

It looks like you might need to enter the Album Id (instead of the Album Name) and this is not available within the new Google Photos interface.

Visit this URL in your browser and you'll get an RSS feed of your albums.
https://picasaweb.google.com/data/feed/api/user/<User Id>

If you then hover over (or click on) an album, you'll see a 19 digit number at the end of the URL. This is the Album Id which you can use in the WP-Juicebox interface.

I've tested this myself with an album I created today in Google Photos and it seems to work fine.
Here are the details if you'd like to try to display it yourself (just for testing purposes).
Google User Id: 109901943277912891450
Google Album Id: 6278925468933743905

I hope this helps.

Edit:
Also, visit https://picasaweb.google.com/<User Id>/<Album Id> (corresponding to the album that you are trying to display) and, in the right-hand sidebar next to the thumbnail representing the album, make sure that the visibility setting is 'Public on the web'. If the visibility is set to any other value (e.g. 'Limited' or 'Only you'), the click the 'edit' link and select 'Public on the web'.