EasySocial Removing a Custom Field

If I change the Profile Type>Custom field - Joomla User Password to require 8 digits rather than the default 4 digits when will this force existing users to change their password length...

1. The next time the user logs into the system?
or
2. only when the user chooses to reset the account password using - forgot my password link in the login form and if the user edits the password field in the account settings within the user profile?

I will get a local host instance setup to conduct this type of test in the future....

Todd