How do I Direct plex where to find movie files ( installed new hard drive and was using a passport.
Try editing the library and adding the new source - https://support.plex.tv/hc/en-us/articles/200289266-Editing-Libraries
Or follow this - https://support.plex.tv/hc/en-us/articles/201154537-Move-Media-Content-to-a-New-Location
