How can I change an account with a shared user to a plex user with login without the history and watchlist disappearing?
If the user also has too many rights in the home, the rights can be restricted so that the plex user cannot edit the admin account.
Can this only be solved with PIN input?
If you mean from a Managed account to a regular account then there is no built in way to do that at this time.
Afaik the third party app Webtools has a function to transfer watch history from one account to another. But I don’t think that transfers watchlist since that is not actually saved on server…