Does not work to stop User2 from seeing User1's screen if User1 is signed in locally.
- Set Windows Security as only authorization method.
- Added only User2 permissions on host.
The remote computer can connect using User2 Windows credentials even if User1 is locally signed in. Thus, User2 can see what User1 is doing and has access to all User1's files.
(Also, If no local user is signed in locally, remote computer can connect using User2 Windows credentials, but that doesn't stop User2 from signing in to Windows with User1's credentials if User2 knows User1's password).