Hi, this may be a dumb question but I can't seem to find the page where you can change your avatar border for the little thumbnail you get in the newsfeed. Any help would be greatly appreciated.

It's indeed not a straight forward way, but now it's on Kumos. So you go to Kumos, click on your avatar thumbnail in the upper right corner > account settings > profile cosmetics > avatar borders

The alternative way I sometimes also use is via legacy > click on wardrobe to go to new.subeta > Personal tab at the top of the page > cosmetics > and that has a direct link to kumos :P

This was so helpful, thank you so much!!