When I try to set another standard user (named "Owner") to an Administrator by clicking "Allow user to administer this computer", the box doesn't check, and instead I get a pop up window that reads "You must restart the computer for your changes to Owner's administrator settings to take effect."
All I can do is select OK and the box for making the standard user "Owner" an admin is still blank.
I've attempted to do this from both the Admin account, and the "Owner" account. Logged out of both users and also restarted the computer. None of these steps have made any difference.