If each line to the bay has its own adjustment, you should be able to adjust one bay to your liking with the pressures set where it works for you, then adjust the other bays one at a time without changing any of the pressures.
I run about the same pressures as cantbreak80 and 2Biz - I prefer low pressure settings on the foam brush so it won't spit liquid when it first comes on.
I have turned on all six bays at once with foam brush, and the foam stayed the same as I had set it one bay at a time. I don't recall if I've tried it with the tri-foam, but I've seen four bays being used at once and it didn't seem to change.