This subject is like a bad penny; it just keeps coming back. Perhaps there should be something about it in the rules? Or in a sticky? Or maybe a strong warning in the explanation before choosing a username?
It doesn't come up very often, so probably doesn't warrant a stickie. Just PM a Mentor in the forums you frequent, and if that doesn't get a response soon, Report one of your posts to make the request.
Actually, I think it does come up pretty often. I agree with Lisab. If there's a way to put a more detailed explanation or warning into the sign-up process, that would be the best approach. Otherwise, I think we need an FAQ link back with information about username changes in it. We used to have an FAQ link, but it has disappeared, and might have mostly included outdated FAQs. Or, maybe it can be put into the library?
Well, based on the number of warnings the Mentors issue to new posters about not reading the rules, I'm skeptical about adding anything there making any difference. We get about 1 name change request per quarter, which seems to be handled fairly well by the Admins, IMO.