I have all 4 banks working on a 18MZ. Which is set up on idle switch (normal, idleup 1, &2) with the 4th bank on Throttle hold switch.
Pick can channel for bank switching
Go to AFR (D/R) - (In Model Menu)
If you have the model connected to the Vbar software- reduce end points in AFR (mine was 65% for bank0 , 60% bank2)
For bank 0 even if it registrars as bank 0 at 100% reduce anyway because this helps when setting up bank 4.
off set the center point to give you bank 1 using x offset Exit AFR menu. (this could also be don in the sub trim menu)
Go to Prog. Mixes (In Model Menu)
Set master to a hardware switch in my case this is the throttle hold switch.
Set slave to the bank switching channel
Just above where it says master on my radio which are initially set to INH, ON, & Speed
select on, changes this to logic, and this will display a menu with the following: left sides single & On, Center has INH, Logic, AND, Right side Single & On. select the right side ON.
select your switch (mine was throttle hold)
Select on/off then your activation position
flick the throttle hold switch to activate the mix then offset line until it activates bank 3.
Note I did a separate off set for each idle position (flick switch to idle 1 to check it was at bank 1, then flick throttle hold switch to check it was at bank 3, then then off throttle hold to ensure it went back to bank 1, then the same with switch set to idle 2 (Bank 2).
hopefully this all makes sense if not let me know & I will try and upload some pictures or pm me.