The other day, I was fiddling with my Nixon watch (yes, that’s the company name with no relation to the dead president). I was just trying to resynchronize its seconds-hand (“seconds-LCD”?) with my computer’s clock which I had just synced with an Internet time server (not literally an atomic clock, but yet kinda in an A-to-B-to-C sort of way). As I was pressing buttons, trying to remember how to get to the time-setting screen, I ended up putting my watch into 24-hour mode. Yeesh.
Thus the saga began. I ended up finding the watch’s manual on their website and I read over about how to set the time. Much of it was fairly straightforward, but the section on setting 12-hour vs 24-hour time simply said “You can set for 12 hour or 24 hour mode while setting the hours”. Well, that didn't really help much. I fiddled with the watch for about ten more minutes until I figured out how to do it.
Most (digital) watches support both 12-hour time and 24-hour time. And, they generally swap between the two modes with a 12/24-hour selector within the time-setting screen. That’s where the Nixon guys decided to be different. Rather than do something that I expected — an explicit 12/24 mode selector — they just built 24-hours time right into the hour-setting sequence. A normal watch might have the hours cycling from 12:00am to 12:00pm through to 11:00pm and, after switching to 24-hour mode, 00:00 to 23:00. But, in this case the sequence was just one long loop: 12:00am to 12:00pm to 11:00pm to 00:00 to 23:00 to 12:00am (and so on).
So, if you have a Nixon watch and you end up getting it stuck in 24-hour mode, don’t worry — just keep advancing the hour and eventually you’ll get back to normal time. Or, I suppose that you could be the type that likes 24-hour time but ends up getting stuck in 12-hour time (which could happen too). Still, you should be able to use the same steps to get back into the time you’re used to.