I bought a cheap-ass watch from Wal-mart. It is an Athletic Works thing, and the manual supplied does not match.
My watch has three buttons - one in the lower left, and two on the right (plus a light switch below the face). Somehow or other, the effing alarm is set and I cannot turn it off. The manual and everything I found on the Internet says “Press the fourth switch”. Ain’t no such.
According to that fount of wisdom, Yahoo Answers, the trick is to press two buttons at the same time, on the right hand side. No idea if it’ll work, but worth a try.