Mogul scroll wheel adjusting the volume only?

[subzero1313]

Idk why, but the last few days, anytime I use the scroll wheel all it does is raise or lower the volume. >.< Its minor, but annoying as hell. I try scrolling through texts and it just changes the volume. Anyone know how to change it back(preferably without soft reseting) or even what causes this, so I can avoid it lol