As title, I have a headset that has +/- and pause/play buttons,and those buttons only can be used for change volume and paly/pause if i press 1 time. I know if I press double on midle button, it's play next track and tripple is previous track, but it too hard to control playback by this way. So anyone can show me how to make +/- button can be used for control next/previous track with 1 time pressing.  thx so much!
P/S: sorry for my bad english