BB Curve :: How To Find Initial Key Store Password

I have an older Curve, and recently changed my gmail password. For the first time I can remember, the phone needs me to enter the Key Store password. (T-Mobile has a security certificate with some issue, and I need to tell the phone, "Trust Certificate".)

I don't think I've ever dealt with Key Store password before. My PIN doesn't work. I have never enabled the phone's Password, never set the password.

Searches here in support plus reading the User's manual for this model 8320 tells me lots of info about the Key Store - including, I might have to reset the phone (and lose lots of data) - however no where have I determined, how was this password initially set? When I reset the phone, how do I even find out what the new password is? Is this something RIM sets, or T-Mobile sets, or do I set it? (Yes I see that I can change it - but only if I know what the existing password is.)