“I have already changed it a lot of times but all require for road vehicles not for air...” go into main menu [esc] > settings > mouse (forgot the name of the thing you had to press but it's something with ''mouse") press that and then turn off "fly with mouse" (i don't know if that's your problem it maybe is or maybe isn't but i hope it helped.
I'll do it on s3. Killing montage with knife....
Proceeds to show melee kills