I'd be happy to take a closer look to see how we can help get you up and running. We'd like to gather more information about the issue you're running into. Are you using a Roku TV or a Roku device? Does the issue only occur on a specific channel or all channels on your Roku device? With more information, we will be able to assist you further.
In this section, I also wanted to suggest that you may want to try to do a forced factory reset if every other suggestion has failed to fix the tv's sound. You will want to attempt this while the tv is powered on and then use a pen or small item that will fit in the small reset buttonhole. Hold it in for about 20 seconds or until the tv begins a complete reboot. If this still does not fix the sound issues, I would look into the tv's warranty for other options.