Locking of individual applications on the KRZR phone?

If you lock individual applications (eg calls, messages, phonebook, etc)on the KRZR phone with your OWN password not the default password that the phone gave you…is there a way someone else can bypass it and unlock it with a different one? What I mean is can they override your password with theirs??? Or is it that the only way they can unlock your phone is with your password ie the own your set for it.

I set a password for this and for some reason my boyfriend ws able to unlock it..I didnt write it down or anything it is in my head and its not a common number or something he knows like my birthday or whatever it was a different number…and yet still he was able to unlock it…So is there an overriding code to unlock my password or did he see me type it in or something???

Any good suggestions?