Turning on bluetooth plays a song

[Hexad Tom]

I have a G4 for my first smartphone. About 2 weeks in, it suddenly started playing music every time I turned on my bluetooth headset (a Plantronics Voyager Legend I have had for some time). Does anybody know what happened to start this (something I did (likely), an update of the phone's firmware, or an Android update (I have Lollipop, I'm not sure which revision))?
How do I see which Lollipop version I am running?
How do I get it to stop playing a song every time I turn on the bluetooth?

 

[bberryhill0]

Software version is at the bottom of Settings in About phone.

 

[Hexad Tom]

Thanks; it says I have version 6.0.

 

[Hexad Tom]

I think I have it figured out. I managed to turn on the bluetooth setting on the G4 to connect for media audio (as well as the setting to connect for call audio). I turned this feature off and the behavior stopped.