How to change code on electronic door lock?

[markjabari]

I live in an office-tel and instead of traditional locks and keys all of the units use an electronic keypad for entering (which means no more lost keys coming home from hongdae and calling the locksmith, yey!). I asked my boss how to change it and she wasn't sure and said to check with my co-teachers, they didn't know either. Does anyone here know? It looks the same as every other one I've ever seen in Seoul. I'm guessing it has something to do with the pinhole on the inside of the door? I assume the process is something like sticking a pin in it, entering my old code and then new one twice... but I can't figure anything out.

If you must know why I want to change it. I have had to give it to delivery men twice who just showed up with a large package ignoring my instructions on gmarket to call first to arrange delivery as well as an ex-girlfriend who likes to show up randomly in the middle of the night sometimes.

Any help would be much appreciated. I'm sure a locksmith could show me how for all of 10,000 won but I thought I'd check here first.