Unable to change my avatar.

Whenever I go to "edit avatar," there is no option to change my avatar and I cannot deselect "Do not use an avatar."

You actually can't change it - your forum avatar is actually your character in the game, and it's appearance is determined by whatever gear your character is currently equipped with (hence why my avatar is wearing PLD AF, as that's what Enki was wearing when I last logged out of the game. ;)).

Okay thank you! I was actually unable to see my avatar at all, but for some reason it appears to be showing up now.

Oh yes, that seems to be just a bug with the forum - I've noticed that too whenever I post my avatar and character details (like character name, class and level etc) do not show up initially - only through refreshing the page via my browser does all that finally load. One of those weird foibles of VBulletin I guess. :p