No suggestions, as I use Spektrum radios, and whatever it is that comes with the Iris+. It took me at least an hour for me to figure it out on my rigs. Then you have to decide which switchs you want to use, etc. etc. BUT, you’ll get it. Then figure out channels 7 and 8 on Mission Planner! One of the Futaba guys will chime in, I’m sure.
I don’t own a Futaba radio, but what you need to do is mix both switches, so that you can have the desired 6 flight modes.
That’s how I’ve done with my Taranis Plus Radio, I have 6 flight modes all working fine. Once you’ve done the mixing, you will need to do another radio calibration.
I would suggest doing a look up on “Futaba Switch Mixing” Or something along the lines.