Volume goes up or down by itself
I have the same problem on two different TV's and Roku devices. The problem started on both TV's about 3 months ago.
Roku Streambar 2A10CD012475 on an LG TV
Roku Ultra KW9992249882 on a Sony TV
I experience the same on both devices.
Most of the time I am using the Xfinity Stream Roku app but it happens on other channels too.
It happens after the TV has been on for a while. The volume will drop but not all the way off, maybe down to the equivalent of 12 setting , or the other scenario is the volume will go all the way up to the point it distorts, To resolve I back out of the channel I am watching and go right back in and the volume will be normal. I removed the Xfinity app and did a system restart on both devices and still have the problem. Sometimes it won't happen for a couple days and other times I will get it 2 or 3 times a day.
Kent