As of the recent update, they locked the Avatar to correspond your current selected character at the forum settings. You can change the Avatar via selecting a different character (I think) only, as far as I know, which is bad, if not for anything else, then for the reason that some of us (such as me) do not want an avatar, at all, especially if they can not specify a custom one!

Such is life. ^^;
Perhaps if enough people will complain, they will change it.

What comes to the pumpkin heads... I don't know, possibly if you have it equipped and log out, it updates to it? I haven't got it so I can't try it out, either.
I have a feeling you will and can only have them on during the event(s).


For reference, the update of which I was... referring to: