How do I control bitrate/quality?

The bitrate controls are accessible via a URL parameter, along with width/height. Something like https://VDO.Ninja/?view=yyyyy&bitrate=10000 will let the viewer request different bitrates. The value is in kilobits per second and the default bitrate is 2500.

Read more here: &bitrate, &audiobitrate , &width, &height​

The viewer sets the bitrates generally, although you can set maximum allowed bitrates as the publisher of a stream. See the advanced settings in the wiki for more help here.

Bitrate controls work best in Chromium-based browsers. Firefox and Safari have limited support.

You can improve audio quality in the same way, by increasing the &audiobitrate, but you can get better results by just disabling noise and echo cancellation instead.