You need to use either Hdmi ARC input on your tv, if it doesn't have one then you use combination of regular hdmi and optical to attach the soundbar to your tv. The ARC allows video to go one way as audio goes the other with one cable. Witout ARC you have video go to the tv from soundbar through the normal hdmi cable, then sound from the tv go to the soundbar via the optical.
Edmund
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.