Select audio Channel when converting

[SullyPanda76cl]

Hi,
I have mkv with several sudio channels
I'm converting the video, and only want to include 1 audio channel

I'm aware of the old 2013 solution: https://forum.videolan.org/viewtopic.ph ... 85#p390959
But seems to be for another version

I'm also aware of whatever workarround (use mkvtools, etc)

The question, then, is: How to select 1 audio channel when converting?

thanks!