Hello Gypsyfw,
To re-enter your user name (or change your user name), go to Ultra Hal's "options" menu, and click on the "General" tab. There you will find places for your name and the name that you want Hal to use.
You can also click on Hal's "startup" tab and control what Hal says to you as a greeting.
As Hal learns, Hal associates much of his learning with your User Name. If you want to create two different personalities (and two different sets of "memories" for Hal) you can do so by establishing two different User Names. Hal will "remember" when you switch back to a previously-used user name.
Sincerely,
Don