Audio Tracks are custom mixes within OBS to let you route audio for specific things (e.g. to stream, to recordings or VOD track).
This gives you the ability to route certain audio sources (e.g. a video, music, microphone) to certain outputs, or even multiple outputs!
In a recording or stream, you can have multiple audio tracks.
Each audio track contains a mix of the sources that are active on the moment of recording. Per source you can select in advanced audio properties on which tracks the audio should be mixed in. By default all sources are on all tracks.
When streaming to Twitch, you have an option to output an extra audio track which will be used in the Video On Demand (VOD) and clips of the stream.
We recommend you take a watch of this video (~ 3 minutes) to help you get started.
https://www.youtube.com/watch?v=cWLk42VyxJE
By default, the Vertical Plugin will use the same settings as your main encoders for streaming & recording.
If your main OBS streaming settings have Audio Track 1 selected, and you have “Use main OBS settings” selected on the Streaming/Recording settings within the Vertical Plugin, then this will also use Audio Track 1.