Password expiry notification

Domain controller = Windows 2000 server
I would like to know how to change the warning message window when a user logs on that their password will expire in xx days.
Is this a global setting or an individual setting?
Password policy is to change every 30 days but it seems that some users get a warning up to 12 days prior. I would like to change this to 3 days.
Some help here would be appreciated