The quality of video can be set with encoder_min_qp. The higher this value is, the more 'blurred' the image will become. A value below 5 probably is not especially noticeable to the human eye and can increase latency significantly. Parsec automatically scales this value based on network performance. The default value for this is 25. If you're still seeing blurry video, try increasing your max bandwidth in the settings tab of the app.