Headphones don't work & music automaticaly starts

I have a Samsung trend plus. When I plug the earphones, the phone recognizes the connection and shows the earphone icon and gives the earphones connected massage. Then automaticaly starts music, which is not normal. But the sound comes from phone's speakers instead of earphones. I can barely hear the music coming from the speakers. And even in full volume setting, it has very low volume. I tried the earphones in my computer so it's not earphone problem. I tried restarting...