What happened to the avatar "windows"? They're circular now. Did I miss the memo? 
Apparently so.Did I miss the memo?
That's a board-wide option, not something individual users can control.From the XenForo post...
That said, some people may prefer non-round avatars and if that's the case you can use this new style property to make them square again:
Changing this value to 2px will give them the same appearance as XF 2.0.
Then I guess it's back to the avatar design studio.
That's a board-wide option, not something individual users can control.