Volume goes up or down by itself

I have noticed exactly the same thing with two of my TVs. I have 3 TVs in total. A big screen LG that has a cable box and no issues. The other two are a Samsung and LG and both have Roku devices and mostly use the Xfinity Streaming App. I noticed it just a few months ago as well. So it seems there may be an issue with the Roku streaming device. It must have been from an update (my best guess?). I was literally about to buy two new TVs thinking the speakers were going out or the TV was going bad. Had my parents over, who also have a Roku and they said they are having the same exact issues. It can’t be coincidence. We need support @Roku, and we need some answers, please!