Audio tracks

[BG Davis]

I'm hoping to get clarification on how the audio tracks function.
There are spaces for 4 audio tracks.  But if I add and enable two or more of them, I only hear one.
Why are there spaces for 4 audio tracks if only one can be audible?
Thanks for any helpful explanation or guide to full explanation.

[eumagga0x2a]

Avidemux can play only the first enabled audio track, it can't mix different audio tracks during playback or editing. Some video players are capable of playing multiple tracks at the same time: e.g. QuickTime, at least on macOS, will play all audio tracks in a mp4 file marked as default simultaneously (and Avidemux saves all tracks as default tracks in a mp4 file because otherwise they are not selectable on command line in VLC  ).

When saving a file, Avidemux will include all enabled audio tracks (e.g. it supports up to 7 audio tracks when loading a mp4 source video). As the audio tracks dialog is limited to 4 tracks max, a higher number of tracks mandate usage of scripting when these tracks need to be re-encoded.

[BG Davis]

Thanks!