There is another Post about the doors on the default 737 where I have posted the following; here is the answer. Go into your main Key assignments menu and change Shift + E to any SINGLE key. I am using \ (back slash) as it is not presently used for anything else. When you press \ main door will open (or close) when you press \ Release your finger, and press 2, or 3, other doors/cargo doors will open (or close)
