Audition method of adding mono audio track to multi-channel
Open AU software, click "multi-track" at the top left, click "browse" in the pop-up window to set the storage location, and then set the file name. Finally, click OK, right-click the blank track, click Track, and then click Add Mono Track to finish the operation. This is why Audition adds mono to multi-channels. After reading this tutorial, you will know what to do. More AE graphic tutorials are in the "Articles", click to learn more.