Thread:ADour/@comment-5111077-20151112084248/@comment-16461120-20151112090732

It's been years since I was on the admin side of Wikia, so I'm not sure where I'd even check, but I don't believe there's any way to preset the thumbnail on any given folder. It's likely based upon some formula like how many times the images have been viewed, similar to how the default arrangement of a category is often in order of most visited.