Thank you for your rapid response.

I set the Large Screen Mode but now only thumbnails are displayed. The link to the full image is not working on small screens on mobile only.

http://lynnjaye.com/?q=node/135

enableLooping="true"
    galleryTitleHAlign="CENTER"
    backgroundColor="rgba(249,237,222,1)"
    showOpenButton="true"
    useFullscreenExpand="true"
    showThumbsButton="true"
    imageTransitionType="CROSS_FADE"
    imageScaleMode="SCALE_DOWN"
    captionPosition="OVERLAY_IMAGE"
    enableAutoPlay="true"
    autoPlayOnLoad="true"
    showAutoPlayButton="true"
    buttonBarHAlign="CENTER"
    indexPageName="coastlines.html"
    imageVAlign="TOP"
    thumbsVAlign="TOP"
    thumbsPosition="TOP"
    screenMode="LARGE"
    languageList="Show Thumbnails|Hide Thumbnails|Expand Gallery|Close Gallery|Open Image in New Window|Images|Next Image|Previous Image|Play Audio|Pause Audio|Show Information|Hide Information|Start AutoPlay|Stop AutoPlay|AutoPlay ON|AutoPlay OFF|Go Back|Detailed Information and Pricing|Share on Facebook|Share on Twitter|Share on Google+|Share on Pinterest|Share on Tumblr|of"

The workaround is good. Much thanks.

The bug noted above whereby the default value of maxThumbRows (1) is not respected on small screen devices when screenMode="LARGE" has now been fixed in Juicebox v1.4.4.
Please see the Upgrading Juicebox support page for instructions on how to download the latest version and upgrade existing galleries.
Please see the Version History for a list of changes between versions.

@walter@web.de

Unfortunately, there is no way to show the Shopping Cart icon in Small Screen Mode. (Juicebox disables the Shopping Cart icon in Small Screen Mode as the Fotomoto window does not fit on smal-screen mobile devices.)
The only way to ensure that the Shopping Cart icon is shown is for the gallery to be displayed in Large Screen Mode (by setting screenMode="LARGE").

Maybe you could use a different Button Bar button to achieve the same effect.
If you use linkURLs instead of purchaseURLs, then the Open Image button (showOpenButton="TRUE") will open your linkURLs.
If you are already using the Open Image button (for images), then you could perhaps override a different button which you are not using (such as the Email Button).
This is not officially supported but you might like to try it.
Here's some sample code which will display the Email Button and open the corresponding purchaseURL when clicked. (It uses the Juicebox-Pro API to fetch the current's image's purchaseURL.)

<script src="jbcore/juicebox.js"></script>
<script>
    var jb = new juicebox({
        containerId: 'juicebox-container',
        galleryWidth: '100%',
        galleryHeight: '100%',
        backgroundColor: 'rgba(34,34,34,1)'
        showEmailButton: 'TRUE'
    });
    jb.onInitComplete = function() {
        $('.jb-bb-btn-email').empty();
        $('.jb-bb-btn-email').off('click');
        $('.jb-bb-btn-email').click(function() {
            var index = jb.getImageIndex();
            var info = jb.getImageInfo(index);
            var url = info.purchaseURL;
            window.open(url, '_blank');
        });
    };
</script>

You could then change the Email Button's icon to something more appropriate (see the Custom Icons support section for further details) and also change its rollover tooltip text (via the Language List configuration option).

As I noted above, overriding Juicebox's regular functionality is not officially supported and my sample code is not fully tested but it should hopefully work OK.

I hope this helps.

Just a short note to let you know that allowing the Shopping Cart Icon (and thus Fotomoto) to appear in Small Screen Mode is on the 'to do' list (although I do not know when it might be implemented).