I am on my second set, and same issue has occurred for me again. First I thought it the firmware update... it's not.... I thwn thought it was the cushions for the earbuds and changed the sizes, removing them altogether helped but not good solution.... resetting to factory didn't help.... someone said online they think the headphones think they are 5.1 and attempting to compensate.... not really sure... when I talked to Samsung they denied this was a problem until I pointed out the fact this has been posted many many times on there own forum... at which point they ended the converstation and said to swap the units...
I wish I had an answer but I can I have tried just about everything. The headphones are an great concept but Samsung missed the mark...
Not sure if this will help, but the stride distance is off between 1/2 to 3/4 miles when running on a treadmill or running outdoors... heart rate and calories are pretty accurate.
Good.luck on the volume, I am hopin Samsung will issue a patch to figure out the problem