It should be noted that your "username" should always be a match to your username here in the Forum. If it's not, then if we ever enable single sign-on, we'll have to fix your account to allow you to log in again once that happens.
But if you're wanting to change the other name that's displayed in lists (built from your first and last names that you entered when you first enabled your account on the competition site), then I can do that for you personally, for now. I'm hoping to make that something that you can change yourself at some point in the near future, but for now, I need to do it manually for you.
Anyone who wants to do that should send me a PM. Please let's leave that sort of thing out of the discussions here - just PM me and I'll take care of your request. Thanks!