According to page 10 of the user manual:
1. Press the Power Level button for 3 seconds.
2. Use the number buttons to enter the current time.
You need to press at least three numbers to set the
clock. For example, if the current time is 5:00, press
5, 0, 0. The display will show: 500.
3. Press the Power Level button.
4. Use the Power Level button to select AM / PM.
5. Press the OK/START button.
6. A colon appears indicating that the time is set
We hope you find this helpful. ^Lo