How do I change my lock screen password?

[AC Question]

I can unlock my phone with my lock screen password, but when I go to change my password it's saying it's wrong and I need to "try again." The password works fine unlocking it, but the same password will not let me change it. I do NOT want to reset my phone if it's at all possible.
Can anyone help me?

 

[TJA3500]

Is your password longer than 16 characters? If it is, the lock screen will only allow the first 16 characters but when you go to change your password it will let you put the whole password in.