must be complicated.
It's not complicated at all. But the Fiio rep told you to check "All Music" in the Fiio Music App and you went to settings/general/general apps and have no idea what "disable" or "force stop" means. From that I am pretty sure that it would be easier and quicker in the long run to guide you through in an online call, rather than try to tutor you through here.
But I'm happy to give you pointers in here so you can give it a try.
You're using Fiio Music app to listen to your music, right?
So you turn on your DAP and you open Fiio Music.
From that first screen you see, choose "Local Music" - it's just above the middle of the screen.
From the row of icons at the top, the center one (box with a note in it) is "All Music". If you have scanned your SD card in Fiio Music, this will show you all your albums.
The one on the right (folder) is the one that I use exclusively. It will let you browse your folders on the SD Card. If you are frequently adding or deleting albums, this might be quicker and easier for you. You don't get such a pretty interface, but it's fast and if you organise your folders (I do) then it's easy to find what you want.