After more than three years, I sure hope you have your answer, but if not, I have just discovered mine for my Panasonic Hybrid System KX-T7030 display phone. The manuals are absolutely useless.
For setting the display on the phone:
Do not pick up receiver.
Press phone's Pause button. "Program" comes up on display.
Dial *#1234. SYS-PGM No? will pop up.
Dial 000 (zero zero zero)
000 Date/Time will show.
Hit Sp-Phone button. This will take you to the date screen. To change year, month, day, enter the correct number and press the FWD/DND button. To pass what is already a correct number on that display screen, hit FWD/DND. To go back to a previous item, use the Conf. key, or press FWD/DND multiple times.
To go to the next screen, for Time, hit the Sp-Phone key.
Use the same process here: FWD/DND to bypass entering, or once the correct time has been entered.
For AM/PM, you will need to use the Auto Answer button as your toggle key.
When you have adjusted the settings to your satisfaction, hit the Autodial button to save.
Robin L., September 2008