I have the same problem I can not change date and time

Setting the date:

1. Press the CALENDAR/CLOCK Key. The default date will appear.

2. Hold the TIME SET key down for 3 seconds or until you see the first
digit begin to blink in the display.

3. Input the correct date.

4. Firmly press and release the TIME SET key. The first digit should
stop blinking and the date is then set.

Setting the time:

1. Press the CALENDAR/CLOCK key. The default time will appear.

2. Hold the TIME SET key down for 3 seconds or until you see the first
digit begin to blink in the display.

NOTE: The seconds will disappear.

3. Input the correct time. If you need to adjust to AM or PM, press
the AM/PM accordingly.

4. Firmly press and release the TIME SET key. The first digit should
stop blinking and the time is then set. The seconds will again be
displayed.

Follow by pressing the CLEAR key to return to the calculator mode. To
return to either the TIME or DATE, press the CALENDAR/CLOCK key to
toggle between them.

NOTE: If unsuccessful attempts to set the date and time have been made,
please first confirm that the piece of paper/plastic in the battery
compartment on the bottom of the unit has been removed. Then reset the
unit by inserting the tip of a ball point pen into the "RESET" hole on
the bottom of the calculator. The calculator should be on and in the
"Print" mode so that you can hear the calculator reset.