Plex server settings sometimes become invisible or grayed out due to incorrect Registry settings. Therefore, you can reset it by deleting some of the Registry values. For that, you need to go to this path: HKEY_CURRENT_USERSoftwarePlex, Inc.Plex Media Server. Next, find these values PlexOnlineHome, PlexOnlineMail, PlexOnlineToken, and PlexOnlineUsername, and delete them. Finally, close all windows and restart your computer.