Hi lunalovegood,
From your quick post, I think maybe you want to develop your app with variables.
If you would like to use this variable to make it "switchable" control, you need firstly initiate the variable somewhere before updating the value in this variable in a new value (!var).
If you want to test the result, for example, you can create a button, with code Set (var1, false), then you create a second button to set on select property to Set (var1, !var1). And, also you create a label to show var1 value. You click those buttons in sequence, and you can see what happen.
My suggestion on your case is that you can additionally initiate the variable in "Screen" property, "OnVisible", or in "App->OnStart". Then, have a try and have fun.
If you still have troubles, let me know.
AMA.
Best regards,
Jason Sun
