First of all, you have to remove the head of the sheer screw.
The easiest way is to just loosen the center screw a little bit and hold the "drum part" and rotate he arm until the next hole lines up. Install the new sheer screw and tighten the center screw. If you can't easily loosen the center screw, or it's a nut, you can still turn he "drum" separate from the arm to line up the next hole. If you couldn't, then the auto pilot would still work normally, which would mean that the sheer screw may not actually be steered.
If neither of these works, remove the center screw or nut and separate the arm from the drum. Install a sheer screw in a new hole, rotate the drum until it can line up with the hole in the arm and reassemble.
Make sure not to overtighten the sheer screw, and it's not a bad idea to use a little blue loctite on the sheer screw. If you overtighten you may weaken the sheer screw and it will sheer much more easily than it should.