Now, click on the find button and then tap on search.First, uninstall the plex app from Firestick by clicking on the setting.Sometimes uninstalling and then reinstalling apps can solve multiple problems. Now click on Advanced and then Switch off Direct play and Direct stream.Now again, turn back to the main page of setting.
First, open the setting from the main menu.To clear cache/ force stop Plex, you need to follow these steps Unresponsive Firestick How To Fix Plex Not Working On Firestick?.