No need to reregister unless you want to change your "User name" - The one you need to login. "Username" is carved in stone and you can always get your current password e-mailed to you at the current address in your profile.

The "Username" is the name you registered with It's basically the only thing you need to remember.

You can change your "displayed" name, password and e-mail address along with other settings in your profile. The button to save any changes is way at the very bottom of the page.

Your Username name is what everything is tied to. If you changed DL-North to DL South the displayed name on all your past posts (past and future) would change as well but your "Username" - the name you used to register - would still be used to login.

There is really no reason to logout. If you have software that deletes cookies periodically you would need to login after it does its thing. If you logout simply to remove your name from "users online" set the minutes to 5. Logging in and out again is only necessary if you share a computer.

Does that help?