How to set fuel?

I request a truck, it arrives, fuel menu pops up, I set it to what I want, but then what? I don’t see a “set” or “apply” button or anything. Do I just close out of the fuel window and it’ll do its stuff?

I haven’t messed with fuel settings in game, but given the weather and time menus don’t have an apply button and their changes take effect as you alter the sliders, I assume the fuel system works the same way.