Track Output Channel Assignment missing

[kaihin30]

Hi guys I just wanna ask about the "Track Output Channel Assignment"

Normally when I drag and drop a footage into "create sequence", those output assignment buttons are missing in the Audio Pannel.

And I have to go back and set up a new sequence again and set the "Tracks" properly in the first place in order to get the "1-2" "1-2" "2-3" "2-3" buttons back.

Is there anyway I can make them showing up even if they aren't there at the first place?

Please help meeee thanks