This clock can be set in two ways. Just click on it or by setting the manually. To set it manually you type the hour followed by h and then the minutes followed by a m. For example, if it is 2:08 you type 2h 8m. 10:30 you type 10h 30m. The clock will continue to show the correct time for as long as you have the window open and active, but note that if others join the room with the clock in it after you have set it they will see the default time until you set it in their presence.