How to record 3 tracks' audio?

I have modified the device toolbar and record one track audio successfully. But how to configure 3 tracks audio capturing? Where should I set up the configuration? More detailed, the better.

Thank you.

If you want to record three channels at the same time you need to be using a “multi-channel sound card” that is capable of recording 3 channels at the same time. Most sound cards can only record one (mono) or two (stereo) channels.

Yes. I select MUTO4pre( as the external audio card. But, I can’t setup the related configuration of Audacity. Could you detail the concrete procedures?

As I previously wrote, multi-channel recording requires special multi-channel hardware. In order for the special hardware to work, requires “drivers” that allow the operating system to use the hardware. Windows driver support for multi-channel sound cards is pretty poor, so most manufacturers use third party “ASIO” drivers rather than Windows drivers. Not all software can use ASIO, so manufacturers generally include standard Windows drivers as well, be these may not have multi-channel support. Audacity cannot be shipped with ASIO support due to licensing restrictions, so what this all boils down to is that multi-channel recording from the MOTU in Audacity depends on the sound card drivers.

Go to the Audacity Help menu and select “Audio Device Info”, and copy paste that info into your reply. Hopefully that will give some indication of how to record multi-channel, if it is possible in Audacity.