How to bind top machine gun sight?

[mommy misato]

I've seen people fire their top machine gun manually and i think it's pretty useful

[OcGuy]

There's the new universal control setting, click Y and chose the weapon control system. From there you can manually choose to use your coaxial machinegun or your 2nd armanent.

[CMDR Emotions]

Open controls and set binds for individual weapons. F2-F5 work well as nothing is bound to them and Warthunder doesn't Alt-F4 without holding it.

Bind F2 to Reset control (all weapons)
Bind F3 for Primary (Main Cannon)
Bind F4 for Secondary Weapon (Hull Gun, Coaxial AutoCannons, the other gun on the VT 1-2)
Bind F5 for Machine Gun.

Selecting Machine gun will make it fire on Mouse 1 instead of Space, if you dont have a roof gun it won't do anything.
Selecting a Secondary cannon will actually change to it's optics (SB) or barrel sight (AB/RB) and give its own sights.

Faster than using the Utility menu in all honesty since the Utility menu locks your movement controls unlike the quick message menu.