Password requirement strength inconsistent

Hi there. I have set the password settings in s2Member under the Registration / Profile section to be the weakest requirement possible with only 4 characters minimum but when I go to do a test sign up after that it says password MUST be 6 characters. Any reason why that is if the settings allow me to set it weaker? Screenshots attached.

https://fightthefloodva.com/wp-login.php?action=register

Thanks in advance for any help.