I found a couple of online manuals that seemed to show how to change your user alarm code for a Scantronic 9448+ system, but the first few I saw weren't correct.

They were nearly correct but did not say that you had to enter your old code twice.

So, here's what you need to do.

• Press 6 and then Enter key.
• Enter your current code, then enter that code again (4 digits)
• Enter your new desired 4 digit code
• You should then hear a double beep to confirm all accepted

The reason why I had to change it was that the old key used one of the numbers twice, so over time it got dodgy in even recognising that keypress, which sometimes lead to setting the alarm off annoyingly. I change it to use a set of unused digits.