Armitron began making watches in the 1950s and remains one of the leading American manufacturers. Some of the company's watches display military time, which uses a 24-hour clock. Pressing a few buttons will change the mode on any Armitron watch.

Press the top left button on your watch once. The seconds should begin flashing.

Press the lower left button six times until the 12/24-hour format appears.

Press the top right button once to select the 12-hour time format.

Press the top left button once to return to time telling mode.