I have a copy of the operating instructions for phones KX-T7420, 7425, 7431, 7433, 7436 these instructions nothing specific on altering the time, or date on the display.
I don't have the actual telephone connected in order to test it the procedure (I'm only involved in disposing of 2/3 handsets) but the best I can see is to go through the features in the MODE button. The fifth display offers "Feature Access" which may give you some choices, you may just have to experiment going through every feature.
If you would like a copy of the operating instructions ring Jane on 01926 742566 and let me know where to send.
Jane Hopkins, January 2008
