My son gave me his old 8700c and I set a password for the device. The only problem is that it prompts me for a password change every few days and it's becoming a pain.
I do not want to disable the password since I ride public transportation to work and don't want anyone else snooping into my personal communications if I lose the phone or it's stolen.
How can I force the password to be somewhat permanent?
Was his BB on a corporate BES system (if you know)?
Look at Options > Security > General Settings > and change the password timeout there, IF you can. If you cannot, it is BES controlled via an IT Policy from his company.
Password Change for 8700C 
