I have a Sonos Arc with 5.1 in my living room. I also have one Play:1 in the bedroom and one Play:1 in the bathroom.  

I like to have them all grouped when watching TV. The only thing what is a bit annoying is that when I change the volume with the TV remote only the Arc gets louder/softer. The other grouped speakers don't change.  It happens all to often that I decrease the volume on the TV and the sound comes from bedroom and bathroom what is not what I want and it sounds strange.

Is there a possibility to synchronise the volume changes for the entire group when using the TV remote? I know it works when using the app.