Why won't the drill bit remove the screw?

I know this may be hard to troubleshoot online but

***The screw is NOT stripped.
***The drill and drill bit DO go together.
***100% sure the drill is not in reverse

When I go to remove the screw, the bit bounces off it, so I cannot remove the screw.
This happens even when j go as slowly as the drill allows.

The bit retracts into the drill and bounces off the screw...

What am I doing wrong?

I have probably near 100 screws that need to be removed and I will not do them all by hand