ist it possible to claim a room ID (for example: meet.jit.si/roomXY?
Because I use the same room every week and when everybody left the room the password isnt longer set. Is it possible to keep the password?
On meet.jit.si this would require opening the room, setting the password and leaving the browser open. This is by design.
On your own server you could setup authentication and this would prevent anyone but registered users (moderators) to create such rooms.