there are 4 buttons on the top: the two right buttons are labeled EQ and Mode. Most of the time, with this brand new portable speaker, it will only go on EQ. I'm not sure why. It seems to be an extremely easy system, yet I can't figure this out. At times it will be in the right Mode (I like to use my iPhone aux for Pandora) but then stops playing and stays on EQ. What, and why, is that?