Whenever I try to change my display name, it says "Your are not authorized to access this area. Check if you are logged in." I am logged in, but it wont work. Help!

Maybe the 90 day thing?

Yes, that's it exactly. You've already changed your name once since you registered, I believe you can change your name once every six months, not positive about the time frame, though.

Thanks.

You changed your name one month ago tomorrow, so you've got quite a while to go yet.

The time frame for a display name change is 90 days.