It looks like a combination of certain configuration options might be causing the rollover thumbnails issue.
Try changing the imageTransitionTime in your galleries to see if this makes a difference.

At first, I thought the problem may have been caused by a timing issue.
However, on further investigation, I have tracked down two bugs which are causing the problems you are experiencing.
The problem with the caption showing stems from setting screenMode="SMALL" and having the cursor hover over the thumbnails as the gallery displays (which happens regularly in your scenario as the links to your galleries are in the same position in your web page as the thumbnails in your galleries).
The problem with the thumbnails not being responsive stems from the additional setting maxCaptionHeight="700".
I have logged bug reports and hopefully they will be fixed in the next version of Juicebox-Pro.
In the meantime, the only sure solution would be to not set screenMode="SMALL".

If you want to prevent browsers from caching your gallery's XML file, try defining your gallery's XML file with a unique identifier (e.g. the current time which will be different each time the browser loads the page) using the configUrl option in your gallery's embedding code.

<!--START JUICEBOX EMBED-->
<script src="jbcore/juicebox.js"></script>
<script>
    new juicebox({
        containerId : 'juicebox-container',
        configUrl : 'config.xml?nocache=' + new Date().getTime()
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->