My I setup a new Samsung sound bar tonight and I'm having an issue w the Smart TV and HDMI.
UN65MU6290 is the TV.
I plugged in the cable box to sound bar and then the ARC to TV. This worked great. ARC is working etc. Then I label HDMI 3 on the TV as Cable Box so iIcan save it on my app bar. When I go to use the cable box, after using YouTube for instance, I come back to find he HDMI 3 had been forgotten and I then have to relabel and read to app bar.
It's more an annoyance than anything but it used to work fine.