How link 2 mono chanel on sq6

Hello,
How to link 2 mono chanel with a sq6.
I know this function on the Qu series, this is directly a key to select (see photo)
Tank you your answer.

Setup/mixer config/input…
and select stereo

Sadly you have no channel ganging on the SQ, so no way to do a normal ganging of two (or more) faders regardless if they are mono or stereo…