Change New User Default Settings?

Hi –

I would adjust the default settings for new users.

Right now when a new user registers and makes a comment, the system automatically uses there full name NOT their user name.

How do I change this so that the system always and automatically defaults to their user name?

Also, I would would like to set the default to be that the admin bar does NOT show for new users. How do I do that?

Right now, I have to go on and manually change these setting for each new user.

Thanks for the help.