You can override this way:
1 - Copy this folder: /templates/ja_shoe/acm/gallery/tmpl/
2 - Paste into this directory:
If the 'local' folder doesn't exist now, pls create it.
Next time, you can make change to this override file: /templates/ja_shoe/local/acm/gallery/tmpl/style-1.php
Your changes in this local folder will not be lost when updating new version of template.
About the 'hidden-xs', could you share screenshot of the subhead text that you're referring to?