Thanks for your question and for the positive feedback about MLA. I am happy to see that you’re finding it useful. Thanks as well for including your shortcode text and the link to your site (which looks terrific); very helpful.
The text “showing when you hover over to the image to click on it” is taken from the alt= attribute of the < img > tag in each gallery item. Usually, you can copy that to the caption by adding an mla_caption="{+image_alt+}" parameter to your shortcode. Notice the “{+” and “+}” delimiters around image_alt; they denote a substitution parameter.
However, this will not help you because your shortcode includes an mla_alt_shortcode=gallery parameter. This tells MLA to perform the data selection part of the job but then hand control to the [gallery] shortcode to compose the HTML for the gallery display. None of the Gallery Display Content parameters, e.g., mla_caption, are used by the [gallery] shortcode. It looks like your site has a lightbox plugin or theme extension that intercepts the [gallery] shortcode and formats the gallery display. Here is an example of your gallery item HTML taken from your example page:
<dl class="gallery-item">
<dt class="gallery-icon"> <a href="https://www.tours.cadaassociates.com/wp-content/uploads/2015/04/Glacier-NPS_The-Sinopah_Upper-Two-Medinine-Lake_Glacier-NPS_960.jpg"><img width="150" height="100" alt="Image courtesy of Glacier NPS" src="https://www.tours.cadaassociates.com/wp-content/uploads/2015/04/Glacier-NPS_The-Sinopah_Upper-Two-Medinine-Lake_Glacier-NPS_960.jpg"></a> </dt>
<dd class="gallery-caption" id="caption4337"><span class="imagecaption">Sinopah Two Medicine Lake-Image courtesy of Glacier NPS</span><br />
<span class="imagedescription">test</span><br />
</dd>
</dl>
In this example I am not sure where the “test” value in the imagedescription span comes from. If it comes from the image’s Description field you could use an MLA IPTC/EXIF mapping rule to populate the Description with your image credits.
Without knowing more details about the lightbox you are using or how the HTML for the gallery display is created I cannot be more specific. I will leave this topic unresolved and I look forward to any additional information you can give me. Thanks for your interest in the plugin.
