Run Plex server as a Windows system service. That way it does run independently from the logged-in user. It will even run if no user is logged in at all.
But you won’t be able to use hardware transcoding if you do so.
The other way would be to always log in the same Windows user account after a reboot. Then use “Switch [Windows] User” to get to any of your other user accounts.
You have to make sure that only the first user account is starting Plex server.
A third way would be to copy the Plex registry branch of the first Windows user to the other users.
However, this is the least favorable option. Again, you have to make sure that only ever one user is logged on at the same time.
Additionally, if you for some reason log out the server and back in, you might get differing content in the registry for the different user accounts.
And you’ll have to set the LocalAppDataPath registry key, so that all Windows users point to the same Plex data folder location. This location should ideally be located outside of the regular place, because all Windows users will need “write” permissions to it. [HowTo] An extended guide on how to move the Plex data folder on Windows
