Advanced Mixing Options

From Audacity Manual

move output channels slider as desired

click to select or unselect any box. Clicking to select a box when another is already selected will link the boxes if they are not linked, or remove the link if they are linked.

Mix and Render only mixes down to mono or stereo.

There is no support at the moment for multichannel playback of audio in Audacity: playback of a multichannel file in Audacity will always be mixed down to stereo.

When you click File > Export and have chosen the name and format of your exported file, a dialog appears which presents you with the number of tracks you have on screen and allows you to map these as desired to each of up to 32 output channels (WAV, AIFF or OGG) or 8 output channels (FLAC). Currently there is no support for exporting multichannel files when using File > Export Multiple.