Ok, I bought the program. How can I change the a known dataref?

I can see the variable that I need to change: "Heading Mode" to 1. The problem is that this variable is not shown in the actions menu. The strange thing is that, if I use the data monitor, I can see, when I click on the cockpit the button, that the variable is changing. So I'm sooooo close to get it...

Hello, i'm trying to map the HDG SEL push button to the HDG button of one of the two multipanels that I have. I spent all morning but I failed to do it. I set the datarefs.txt from datareftool in the airplane folder and now I have both variables "Heading Mode" that has a value of 1 when it's selecte...