The Minimum Password Length option allows you to specify the length of the password which Memberium generates for your users. For example, passwords that are generated using password generation web hook.
You can set the minimum password length from Memberium -> Settings -> Login page on the Memberium admin dashboard.
The setting will also force users to choose a password equal to or longer than the set number when changing their password using [memb_change_password].
Please note that this option does not require that already existing passwords be of this length.