1) After you add your gallery to a page, click on it again and select "custom template"

2) Select one of the 9 custom templates

3) Click save

4) Exit edit mode and publish edits.

If you are adding a large gallery to a page, the first time it loads there may be a slight delay as it generates thumbnails for each image.

CDN (content delivery network)

Bootstrap Image Gallery comes with built in CDN functionality for CDN services that provide you with a URL.

Simply enable the CDN option by setting it to true and set your URL for your CDN.

Your images will now load from your CDN instead of your own server