The bottom button on the chronograph watches will reset the chronograph to zero. If it is resetting to a number other than zero, follow these steps to get back in sync: 1. Pull the middle knob out two clicks (as if you were adjusting the time)2. Hold the bottom knob. this will adjust the minute and the second subdials. Once they're back to zero, push the middle knob back inPlease email support@donovanwatches if you have any questions.