Spelling typo fixed. Thanks.

To get to your problem. This wouldn't have anything to do with uc_roles, BTW. The code that sets up new accounts is in uc_cart What version of Ubercart are you running? The latest bazaar release I'm working with, the behavior or these options work as expected. If you know how to troubleshoot by editing PHP files you can find the code that displays the new account form fields in the function uc_checkout_pane_customer in uc_cart/uc_cart_checkout_pane.inc.