Changing password

[ab1--]

I changed the password to enter my computer and used as suggested 2 upper case letters, 2 lower case letters, 2 numbers and 2 symbols but when I try to log on only the first 1 or 2 items will it let me type. Also, the original password is still accepting.  When will it let me type the new password?

[ab1--]

I have a further question. When the new passcode starts working, how will I sign in when trying to type the new passcode when I switch the computer on when it only lets me type 1 or 2 or sometimes none of the letters/numbers?