Can't change free look keybind?!

[Tarkus8]

How do I change the free look keybind? Because, you know, it doesn't work! This mess of a game is driving me mad. I set the free look to C, but it also triggers when I press right mouse button, which I'd like to use to fire cannons. So it creates this damnit weird situation of me shooting cannons and triggering free look at the same time. How do I unbind that?