Samsung Propel security codes

I'm going through my phone trying to change my passwords and I'm having problems doing so. I tried looking in the manual and all I could find was how to change the code - not what the actual original code is. What the heck is it?! In order to set a new one, I need the old one and I don't want to sit here guessing at it. I tried the last 4 digits of my phone number, which has worked for most of my other phones in the past. What else could it be? Also, how do I set my SIM card with a new lock code?