for the x max that is a language file.
Goto Control Panel » Languages » Language Editor
edit editbasic.php
look for key AVATAR
Edit it to state the size you wish.

As far as size. The default setting was I believe 80x80 when you installed it.
I believe the setting will only change the uploaded avatars by members not the stock ones uploaded via the control panel.
Not 100 percent on that though never tested it.

Blue Man Group
There is no such thing as stupid questions. Just stupid answers