thank you for your replay. I think, it’s just twitch policy. Quality option works in all standard browsers. And as I know - webView in UWP apps use the same engine as Microsoft Edge. I saw that still available API through usher.twitch… But as I know it’s deprecated API, already no documentations and I don’t want rebuild my app later. Maybe your know email for tech group who can comment this situation, because I don’t know what to do next. App without manual quality changing doesn’t have sense.