A lot of alarm systems, depend on the installer, the alarm unit does not default on reset. i.e the units I use, if I set the last digit of the engineer code to a '9' that code is not over ride able. even back to factory defaults, that engineer code is fixed. Unless, the engineer changes it, only way to reset it is back to manufacturers.
Other already preset zones can be changed via user code, usually 1234 are used as defaults for user, in what ever order, engineer code could be others, IF you have the instructions and you can get access to engineer level, you must not be entering in correct order, engineer level lets you set what can and cannot be part set. check what the code you are entering.
Sheepdog
December 2008