How can I configure s2Member password emails?
s2Member integrates with WordPress for many things related to user accounts, including the sending of passwords. s2Member itself generally doesn't send password emails--that functionality comes from WordPress itself (see one exception, where you can customize the New User email).
If a user resets their password (using the Forgot Password link), for example, that's the WordPress Password Reset functionality taking care of that. If you want to customize WordPress-related emails, I suggest posting a question on the WordPress Support Forum.