Just as you found, the screws adjust the scope. You may have to get the locking rings freed up by backing the screws out to where the locking ring clears the scope tube, and then holding the locking ring with a padded pair of pliers, and turning the screw with a screwdriver to break them loose. Run the locking ring up to where it hits the head on the adjusting screw, and then when the scope is sighted in, hold the screw with a screwdriver and tighten the locking ring agains the scope tube.