How do you switch from driving a vehicle, such as the goliath or the hellbender, to using that vehicles weapons? I've seen people do this without any accomplices in the vehicle. There's a slot under "Configure Controls" for "Weapon Selection," but every time I try to bind a key to it, it doesn't work and when I come back to it, the slot is blank. Anyone else having trouble with this? Or am I just tarded?