Jasco 19242 - Manual (Page 4)

back of the chime (See the chime components picture above). Remove
the screw and take off the door.
4. Locate the chime and pushbutton jumpers shown below.
Chime and Pushbutton Jumpers
5. To change the house code, add or remove jumpers as needed. It is
recommended to change only one jumper at a time and then test the
system for proper operation. The jumpers on the chime and pushbutton
must match exactly.
House Code Jumpers