This question already has an answer here:
Can I put a folder in the top of the main drive (is that the root?) so that the two users of the machine can use it freely. For example, I'd like to put music in it so that both users can import to Rhythmbox. We also need to keep other various files and docs there and we need to edit files created by eachother.
I'm not magnificently knowledgeable of term commands, so if someone could give me reasonably detailed instructions, I'd be very grateful.
If there's a better way to do what I want; I'm listening...
Using Ubuntu 18 (if you want to help with my Ubuntu<>MacOS filesharing problem, please look for my other post).