Mac OS X 10.5 Help
Changing your administrator password
To change the administrator password, you must know the current administrator password.
Since an administrator has broad privileges on the computer, you should choose a secure password for your administrator password.
To change the administrator password:
Log in as the administrator.
Click Change Password.
Type the new password and then type it again in the Verify field.
Type a hint to help you remember your password. For assistance picking a secure password, click the key by the Password field.
Click Change Password.
In Keychain Access, change your login keychain password to match your new administrator password. This unlocks your keychain when you log in.