JBL Bar 3.1 Questions & Answers

Got given a JBL sound system a while back, but found the subwoofer made backfiring sounds coming from the speaker. Scared the hell out of me and the dog, like a rifle shot. Still goes on from time to time, anybody got an answer for this please....oh it's a 3.1 system.

This 3.1 channel model soundbar states that it comes with an Auxiliary cord. So, I can connect to Aux in it? It doesn't mention Aux connection at all

when on the tv ( hdmi arc ) lights up often resulting in slight loss of voice etc when quiet and then someone speaks etc. a quarter second loss of sound then lights up and fine until next quiet few seconds then lights up ( arc ). needs to stay on arc and not off.