Reply to 4 deck mixing with vci-100

Hello,

I hope i will explain this clearly, I have a vestax vci100 without the firmwarekit, but i do use the 1.4 firmware and i also have the latest overlay to work with it.
I know somethings do not work without the Firmware kit, but i take that for granted.
Today is was mixing with 4 decks, but whats the best way to do that? Now i had 2 songs playing at the same time (deck-a and b) deck-a with the bass on and deck-b obviously not, but when i start deck-c i also set the bass at very low, but when i then switch back to deck a the bass is still full, but the rotary knob of the low is still down, how does this work in good order? or is it not possible?