Varies in this case means that you have a default value for the instance variable (likely "False") that you can check by selecting the Object Type that contains the variable directly in the Object Type folder of the project's bar and you have an instance of that object type which instance variable's value is set to "True", resulting in the fact that the defaulting value in turns "varies" in your edittime configuration.
Just make sure to select the instance, the value set for the instance will stick to it, or at worst, in your event sheet, on start of layout, do some initialisation and set the instance boolean variable's value to True. All instances of your object type will have their instance variable value set to true, but it should do the trick.