Is there a way to change fuel load in Quick Mission option panel? I see the load out listed as 100% but am unable to activate the slider to reduce fuel load to a lower %.

You can but I'm not at my sim right now to go thru it. I think you need to go thru the plane set up and before you start the quick mission. I'm sure someone here can take you thru it.

I see the slider in plane setup. It's just that the slider will not move off 100%. OTOH the slider is functional in online missions! Why it would not work offline is so far an enigma.