Plex Web is just another Plex client. It’s settings are saved within your browser’s cache. Do you have your browser set to clear the cache whenever you close the browser? If so, then this is what’s clearing your login info so you have to login again the next time. Also, accessing your server using 127.0.0.1 or 10.0.x.x will be treated as 2 different clients. Their settings will not copy from one to the other.
