Wanting to switches modes on APM or PX4 is really not intuitive using two switches on your transmitter. You need to have a switch with 3 positions and another with two positions. (2x3=6) modes.
I thought I would design a more "human" or "intuitive" electronic switch. Has six big tactile push buttons and one sun visible LED per mode.
If you're unsure of the current mode, a quick look will show you which LED is on.
Inside are six 20 turns trimmers which let you adjust perfectly each of the 6 modes.
Simple and tested on Spektrum, JR and should work on any Tx that has a pot that you can allocate to channel 5 (mode channel on APM).
Have a look at the attached photos, simple but really helpful.