I've been having an issue with my S8 not keeping the changes I make when selecting a non-stock ringtone or notification. Typically, when I make the change to a customer tone, it keeps for a couple of hours and then reverts back to the stock default tone. I've moved the location of the tones from my internal storage to external SD card and then back just to make sure it wasn't an issue with the location for tone but still keeps reverting. Any ideas?