I had the sound problem with the speakers balance shifting to the right aswell on all versions from 10.2.3 to 10.2.8, tought there maybe a combination of keys i was pressing was adjusting the balance, it's like the brightness controls on F14 and F15, i didn't know they were there until one day i pressed F14 buy mistake. Maybe this is only on the tft screens. Apple have a way of dropping things into the os without mentioning it 