After resetting your password and logging back in to your account, you might see an alert that the system was unable to unlock your login keychain. This is expected, because the passwords for your user account and login keychain no longer match. Just click the Create New Keychain button in the alert.

If you didn't see an alert about your login keychain, or you see other messages asking for your old password, reset your keychain manually:

  1. Open Keychain Access, which is in the Utilities folder of your Applications folder. 


  2. Choose Preferences from the Keychain Access menu, then click the "Reset My Default Keychain" button in the preferences window. This will prompt you to put your new password in; after you enter your new password, Keychain Access creates an empty login keychain with no password. Click OK to confirm.

           



    If you don't see a Reset My Default keychain button, close the preferences window and select the “login” keychain from the left side of the Keychain Access window. Press the Delete key, then click Delete References.

  3. Choose Log Out from the Apple menu to return to the login screen.

                  


  4. Log in to your account using your new password. Your account password and login keychain password now match again, which will stop the keychain prompt from popping up!
If your Mac keeps asking for the login keychain password please follow this link to Apples support article:

Apples Support Keychain Article