It isn't Windows at fault here (and oddly, it isn't Windows at fault for 99.9% of the things people blame it for)... It is purely Rockwell. For some completely insane and idiotic reason, they tag user accounts CREATED IN FTVIEW with a GUID based on the system that created them, and don't manage them simply by name.
It was "YABDD" (Yet another bad design decision) by Rockwell, and serves absolutely no purpose except the dubious one of allowing Active Directory authentication of users. The big problem there, is if you are an OEM, you don't live on your customers AD.
For ALL of my FTView apps, SE and ME, there are only two users, and one is common to all of them. I don't use FTView security for anything, instead, I just use PLC passwords to lock/unlock certain levels of functionality.
The other bloody insanity about Rockwell's security is that it defaults to thinking I'm programming a banking system. NO, I do NOT want "Minimum Password Complexity". NO, I do NOT want "At least 6 characters". NO, I do NOT want "Passwords to Expire".
I wish Red Lion made a full featured SCADA/HMI package, then I'd dump Rockwell entirely instead of just on the things I replace with G3's.