You're better off googling how if you still haven't.

It should be the same way you edit it for other media which I do use Plex for. I just don't for music specifically.

But I can't stress enough that if it's just happening to one item, don't put too much effort I to this.

Some things Plex just doesn't recognize randomly. It is insanely rare and I think it's happened to me twice in a dozen years? And my Plex is large bro

Youll probably never have this problem again, so just Google how to manual make Plex recognize it, even if you have to type all the song titles out. It'll take 15 minutes and you'll probably never have to do it for anything else