I can´t understand you so far because don´t have a good english. I just want to change my nickname to another and that´s all (only once) I have no problems in any forum, web or pc-game to do it, and i change because i want mi nickname to be the same in all the webs.
Anyway, if my nickname can´t change, i can always create a new username, but i dont want do that in first place.