Plex used to work, but I can't find what I did before reinstalling my OS

I’m working on an old HP tower that seems to not like any of the updates being pushed by Ubuntu. So I am still running 16.04. A recent update broke my entire system and I had to reinstall my OS. Since doing that I have not been able to find how I set the permissions for plex to be able to see my media folders.

They are currently split between two drives at the following locations /SharedSpace/Videos & /MyBook/Videos. This all worked last week and now I can’t seem to find instructions that allow plex to access those folders to populate the library.

I also can not find where how to move the plexMD folder from the home directory to a partition that has more space.

Any help would be greatly appreciated.

Here is the output of my df -h command

Filesystem              Size  Used Avail Use% Mounted on
udev                    1.9G     0  1.9G   0% /dev
tmpfs                   388M  6.5M  381M   2% /run
/dev/sda9                20G  2.1G   17G  12% /
/dev/sda6                20G  3.6G   15G  20% /usr
tmpfs                   1.9G   51M  1.9G   3% /dev/shm
tmpfs                   5.0M  4.0K  5.0M   1% /run/lock
tmpfs                   1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/loop0               89M   89M     0 100% /snap/core/6964
/dev/loop1               90M   90M     0 100% /snap/core/6818
/dev/loop2               89M   89M     0 100% /snap/plexmediaserver/13
/dev/sda8                20G  106M   19G   1% /boot
/dev/sda5                20G   13G  5.8G  69% /home
/dev/sdb1               2.8T  2.5T  272G  91% /MyBook
/dev/sda4               1.8T  1.4T  391G  78% /SharedSpace
tmpfs                   388M   44K  388M   1% /run/user/1000
/home/erskine/.Private   20G   13G  5.8G  69% /home/erskine
/dev/sr1                7.7G  7.7G     0 100% /media/erskine/E2938