If you are finding that the chronograph dials on your watch are not zeroing correctly, please follow these instructions as it is highly likely that the watch needs calibrating (very rarely is this a case of the watch being faulty):

Pull the crown out fully, then keep pressing the top button to adjust the top dial until it reaches zero, and then the same with the bottom button to adjust the bottom dial.

Following these instructions, you'll be able to set your chronograph watch to the correct "zero point".

People often accidentally "uncalibrate" their chronograph by pressing the buttons when the winder is out, causing the dials to move off the zero position.