Get back to the Login screen, and change your login name to the name you want to appear with your post. Then tell it to "remember your password". All the other information can stay the same.
Knowing each other's first names is one of the pleasures of this forum. Don't you think so?
I made the mistake of going into the Optiplex section of the forum, and somehow I told it to remember my name. Did THAT cause me problems. I couldn't get back to the Dimension section. I had to go into my "cookies" and delete anything relating to the new forum (new http. so it was easy to find). Phew!