How do you set your preferences?

[RERomine]

Thanks Andy for the information about campaigns. That's what I thought, but wasn't sure.

As for low visibility situations, this is directly out of the online instructions manual:

Note low visibility (less than 40 hexes or so) means that air strikes are unlikely to be allocated, even if set to a positive number in the preferences screen, as visibility is too low at the airfields for flying that day.