By the board in which you posted this, I assume you are referring to forumly details, although I thought I should mention that while you are able to change your forum nickname and password, you cannot change your in-game username. (If you want to change it, you will have to create a new account.) If you would like to change your in-game password, you can do so by selecting the "Forgot your password" function in the golden box at the top of the website, and entering the e-mail that you registered the account with. To change your forum nickname and password, you can do so by going to your Profile, and the rest is pretty self-explanatory through PrettyReckless's picture. Hope this clears a few things up.