In Sophos Central on a single device Last User shows a user that is not logged in, and who doesn't have internet usage rights. And because of this the logged in user who has internet rights is being blocked.

Thank you for reaching out to the community forum.

You can assign a user to a certain device by following the steps listed in this documentation. 

In your current case, you need to re-assign a user on this device since there's an existing one that is reflecting it. 

Let us know if this helps you solve the issue.

By Device I mean Windows Computer.  There is no option to assign a user.  You can assign a user to a login, but that wont help in this case.  It took a few hours but central finally updated itself and shows the right person as "Last User".  I'm going to write this up to an internet problem that it took so long.  Thank you anyway for trying to help.