What does one do if their alternate password on Samsung Galaxy 5 is wrong?

So, my old phone was a cheap $20 Woolworths phone as a result I'm not good at phones. Anyway, I decided to try a lock screen on my new phone my SD gave me and it has trouble recognizing my fingerprint (only works sometimes). In the end I decided the lock screen is too hard and I'll just do a factory reset so my phone would let me change it, but I need my alternate password to do that. I have tried all possible passwords, I am certain I put the correct one in multiple times, so I must have mistyped something wrong when I made it. Does anyone know what to do? Is there an remember alternate password service or something? I've already decided to go to Optus to try and get them to help me out, but if I don't have to that'd be great.