Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
During playback of a video, press the star (*) button on the remote and scroll to “Volume mode” then change to setting to anything other than the current setting. Mine was off, I choose to change it and put it back to off. The sound was back permanently. Give it a try. Worked for me and others. Good luck.
If you press the star button on your roku remote and scroll to the “volume mode” setting and change the settings there, to anything, I set mine to “off” you won’t have to change the volume on every video.