Reply to Speaker issues with my S4

I just noticed an issue with my speakers today. I have my s4 set up in my room, connected to a Logitech speaker system with a left, right, and center speakers. For some reason songs playing on deck A plays perfectly on all the speakers, but on deck B it only plays through the center and right speakers. Is there something i messed up in the settings? I really have no idea where to even look to figure it out as I'm a complete newbie. Any suggestions?