Unable to edit complete mopidy.conf file

I am setting up a Pirate Audio Line Out for Raspberry Pi (latest Buster version on a Pi 4, model B, 4GB), and cannot edit the [local] section of the mopidy.conf file. When I enter “sudo nano /etc/mopidy/mopidy.conf”, the file opens, and I can edit what is there, but the text stops after the [spotify] section, and the bottom of the screen says [ read 54 lines ]. I have made the necessary Spotify edits, and that works fine.
If I type "sudo mopidyctl config, I can see the effective configuration, and I can see that I need to change the media_dir value in the [local] section, but that section is not showing up in the 54 line version I see when I run “sudo nano /etc/mopidy/mopidy.conf”.
As a result, the local music files I’ve added are not being found.
How do I edit the complete mobidy.conf file?