Hello @Sueede48 ,
I use the c button to set the frequency and it works, but I do not use the keyboard…
The +/- description may be misleading. I expect it to work like the alt/heading/speed… bug settings, that have the same description concerning +/-. I do not know if they are meant to be used with the keyboard, but they may have been intended to be used with something like the Honeycomb bravo, where you have one knob to select which value it is you want to change and the other one is a knob that makes use of the plus and minus key binding to increase/decrease the selected value. I think it should also work with the keyboard, if you set c as the com1 selector that shows the +/- description and add two keybindings to the miscellaneous plus and minus settings in the game. E.g. bind the + key to the Plus in-game setting.