How can I set a button to on/off captions, like Picasa?
A button, to the users, on/off the captions.

Excellent Steven.
The second alternative it is perfect to set the defaults options to my galleries.
C:\Program Files\Google\Picasa3\web\templates\juicebox_picasa_template\header.xml
Thank you, Francisco

I am using Juicebox Picasa Template Pro.
How can I to set my defaults Config Options, like these?

<juiceboxgallery
captionBackColor="rgba(0,33,33,0.5)"
captionBackTopColor="rgba(0,33,33,0.5)"
captionHAlign="CENTER"
galleryTitle="0000"
imageScaleMode="SCALE"
importCaption="IPTC"
importTitle="NONE"
maxImageWidth="1920"
maxImageHeight="1080"
showAutoPlayButton="true"
showExpandButton="TRUE"
showImageNumber="false"
showOpenButton="FALSE"
showPagingText="false"
showSmallPagingText="false"
showThumbsButton="TRUE"
textColor="rgba(255,255,255,1)"
thumbFrameColor="rgba(255,255,255,0.5)"
useFlickr="FALSE"
useFullscreenExpand="TRUE"
useThumbDots="FALSE"
useWatermark="true"
>

Now, with Juicebox Pro, it's fine.
Thank you Steven.

http://comvir.tk/temp/201911b3.png

Please, how can I set Juicebox to fit all images to full screen size, like Picasa?

Juicebox's view:
http://comvir.tk/temp/201911b1.png

Picasa's view:
http://comvir.tk/temp/201911b2.png

Thank you Steven.

Thank you Steve.

Using this code on Blogger:
http://comvir.tk/temp/201911a1.png

I received this error:
http://comvir.tk/temp/201911a2.png

This it is the gallery folder:
http://comvir.tk/temp/201911a3.png

This it is the gallery:
http://comvir.tk/gal/1800/

Please, can you help me?

Embedded gallery not display full screen icon.

useFullscreenExpand="TRUE" 
<iframe frameborder="0" height="528px" src="https://comvir.tk/gal/1800/" width="528px"></iframe>

Can you help me?