How to unlock "left alt" key for free look

Hi, is there any way to unlock the “left alt” key for normal use for anything, in my case for “free mouse camera look” which is under the “C” key in default. “Left alt” is for “show mouse cursor” in default and even if I remove this, it still doesn’t work for the free mouse look. Also when I press “left alt” my right mouse click “zoom” does not work.

Is there a way to unlock the “left alt” so that it works normally for a specific thing?