I have a Roku Express (3900x) which does not have the volume buttons. My tv (non smart) volume is controlled by the RCA remote however the volume is triggered to go up and down by pushing any of the arrow buttons on the roku remote. For example, I’m in scrolling thru Netflix and I push the arrow to the right 15 times the volume goes up 15 times. If I push the left arrow it goes down but if I push up and down arrows they too control the volume. I constantly have to keep the tv remote near to counteract the volume the Roku remote changes while scrolling. Help!
It's possible that the IR signal that is being sent to the the Roku device is interacting with the IR signal for your TV. Have you tried moving the Roku device away from the IR receiver on your TV and seeing if this resolves your issue?