(7) How do I change my username?
Usernames are not changeable unless it is to the advantage of the Administration ie: politically incorrect/trollbait/disgusting/improper usernames that somehow slipped through the filter. If you want a different name, you must have an admin close your present account and then you may re-register with the new name.
So if you want to be known as D Unit (or anything else), just PM one of the admins to close your current account, and then you can re-register for a new one.