Cant Change the display name

If you are using the KX-T7730 phone on a Panasonic KX-Txx 308 or 824 system. From the Switchboard / Main telephone ( usually ext 101, 10 or 9 ) with the handset on the cradle press PROGRAM * # followed by the system password ( default is 1234). Now press 604 and then SP-PHONE. Enter the jack number you wish to change ( 01 is extension 101, 02 is extension 102 etc. ). Enter the name ( basically the same as texting on a cellphone ). Press AUTO DIAL / STORE to save your change. To go to the next extension press SP-PHONE. Don’t forget to press AUTO DIAL / STORE to save your change after each name entered. Press PROGRAM to exit program mode and you are done.

Basically, there are 2 ways of programming the date
and time - the short way and the long way.
If you are using the KX-T7730 phone on a Panasonic
KX-Txx 308/824 system:

SHORT WAY:
From the Switcboard / Main telephone
( ext 101, 10 or 9 ) with the handset on the
cradle/hook:
1. Press PROGRAM 0
2. Enter Date and Time
( The format is: yymmdd,
1 to 7 1=Monday 2=Tuesday etc, hh:mm,
0 or 1 0=AM 1=PM ) see example
3. Press AUTO DIAL / STORE to save your changes
4. Press PROGRAM to exit program mode

EXAMPLE:
If the date and time is 3 February 2010 Tuesday 2:15 pm you will enter as follows:
100203 2 02:15 1

LONG WAY:
From the Switcboard / Main telephone ( ext 101, 10 or 9 ) with the handset on the cradle/hook:
1. Press PROGRAM * # followed by the system
password ( default is 1234).
2. Now press 000 and then SP-PHONE.
Enter the year.
3. Scroll to the month with the right scroll key
(located at the right bottom corner of the phone).
To change the month use the AUTO ANS / MUTE
button.
4. Now scroll right again and change the date and
day.
To change the day, again use AUTO ANS / MUTE
5. Scroll right again and the time will appear.
Set the time.
To change am/pm scroll to it, and again,
use the AUTO ANS / MUTE button.
6. Press PROGRAM to exit program mode and you
are done.