This thing has only one button, which is invisible. Its close to the center of the circle. A little bit down, its easy to feel it. Once you press it, time shows up.
Press the button once wait for it to show the time. Press again and hold it this time. You will see the hour and either A OR P next to it. Clearly, its AM or PM.
Next, after you adjust the hour, press and hold the button again to switch to adjusting the minutes. After that, the year, the month and finally the day.
Clearly, its AMAZING!