How to Reset a Master Password on My MacBookby Julius Vandersteen
When you power on a MacBook laptop for the first time, the system will prompt you to set an administrator password -- sometimes referred to as a master password -- with the setup assistant. You enter this password later to install new applications or change system preferences. If you want to change the administrative password, perhaps as a routine security precaution or in cases when you believe it has been compromised, you can easily reset it. The procedure for changing the administrator password is the same in OS X for Mac desktop computers and MacBooks.
Click the Apple icon from the menu at the top left of the screen, and then click "System Preferences."
Click the "Admin" user under "My Account" if it's not already selected. Click "Change Password."
Type your current password in the "Old Password" box.
Type a new password in the "New Password" box.
Type the new password once more in the "Verify" box.
Type a hint in the hint box to help you remember your password. The hint will appear if you later enter the password incorrectly three times in a row.
Click "Change Password."
Click "Applications" in the dock, and then click "Utilities," and then click "Keychain Access" to launch the Keychain Manager, which holds passwords for various applications and sites and is controlled by your administrator password. Click "Edit," and then click "Change Password for Keychain Login." Type the old password in the "Current Password" box, and type the new password in the "New Password" box. Type the new password once more in the "Verify" box, and then click "OK."
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