OK. I'm so stumped and frustrated I'm about to just reinstall Windows 10 to fix this. I just set up a clean install of Windows 10 on a system with a 120GB SSD and a 3TB hdd. Of course I needed to move the My Documents/My Pictures/My Videos/Downloads folder targets to the hdd. What I did was:
Right clicked the My Documents shortcut - Properties - Location - Move. And I selected D: (which is the hdd). What happened is that windows made the ENTIRE HDD into the My Documents folder (there isn't even a "My Documents" folder on the hdd).
I cannot revert the folder location to default because I get an "Access Denied" error.
I looked up this issue which suggested logging onto One Drive and re-locating it to another location. So. I did this and relocated One Drive (which was set to D: for some reason) back to C:/Users/One Drive. This did nothing. STILL getting the Access Denied error.
Please help!!!
PS. It seems the correct way to do this is to create a "My Documents" folder on the D: first to set the target to D:/My Documents?
I don't THINK I'm that stupid. This really shouldn't be so difficult.