You have to set up the autoreturn in PayPal to make it return to the site.

The url I used is http://www.yoursite.com/uc_paypal/wps/complete (change 'yoursite.com' to your own url obviosuly).

There are conflicting messages in different threads about whether you need it or not to get it to autoreturn but from my experience, you do need to enter it in the appropriate place on your PayPal account.

So, that's working now, but it still will not give the new user the role that is supposed to be assigned when the order goes to 'Completed'. The new user is created and they can log in, but do not have the 'Subscriber' role that I set up assigned to them.

Also, the auto email that the new user gets states that the password is for one time use only and that on logging in they will be redirected to a page to change it. I know this is not strictly a Ubercart thing but it doesn't do any of that. You can carry on using the sysetm generated password as much as you like. Any idea where to go to enforce what it says in the email?