I ran into sound issue after I moved a 4K Apple TV to a new room, connecting it to my Samsung 4K television and my Sonos play base. I tried making adjustments using the TV button on the Apple TV remote and connecting sound through the updated sound and quick settings button. I also try to go into the sound system settings inside of the Apple TV. I tried going into the settings inside of the Samsung television, as well as Sonos settings. I found the solution in the Apple TV settings, under remotes and devices. In the home theater control setting, select that the control TVs and receivers is on. Ake sure the volume control is set to auto not HDMI not TV via IR or Samsung via IR. Set to auto to allow adjusting sound using your remote control and coming out of the Sonos.