Connecting Plex to an External Hard Drive



My Plex is currently connecting to a 4TB External Hard Drive while running the Plex app on my iMac. For some reason I keep losing connectivity between Plex and my Hard Drive, therefore giving me a file location errors and such when I try to open a movie, music, etc..

How can I stop this from happening? I have tried two different 4TB External Drives and it happens to both sporadically. The other issue is that I cannot locate where I point my plex app to the external hard drive for the library anymore. Thoughts?

Thanks in advance