Pentax Optio H90 Orange Operating Manual page 188

The following operations and screens use [mm/dd/yy] as an example.
The operations are the same even if another date format has been
selected.
11
Use the four-way controller (23)
to change the month.
12
Press the four-way controller (5).
The frame moves to the day field. Use the four-way controller (23) to
change the day. After changing the day, change the year in the same
manner.
13
Change the time in the same way as in Steps 8 to 12.
If you selected [12h] in Step 7, the setting switches between am and
pm corresponding to the time.
14
Press the four-way controller (3)
to select [Settings complete].
7
15
Press the 4 button.
The date and time settings are saved.
When you press the 4 button in Step 15, the camera clock is reset to
00 seconds. To set the exact time, press the 4 button when the time
signal (on the TV, radio, etc.) reaches 00 seconds.
186
Date Adjustment
Date Format mm dd yy / /
01/01/2010
00:00
Time
Settings complete
MENU Cancel
Date Adjustment
Date Format mm/dd/yy
Date 01/01/2010
Time 00:00
Settings complete
Cancel
MENU
24h
24h
OK
OK