By default, your keystring password is the same as your user password (the password you use to log in to your computer). You can change the user password in the “Users and Groups” preferences, and the keystring password will automatically change to match the user password. If you do not remember the previous user password, you need to restore the default key string. Restoring the default keystring will remove all passwords stored in the keystring, but should allow you to synchronize login passwords with passwords stored in the keystring. Take a look
Update the keystring password tutorial on Mac
1. Open the boot console.
2. Select another key string for access.
3. Choose Keychain Access > Preferences.
4. Click restore My Default Keychain.
5. Choose The Apple menu > Log Out. When you log in again, store the current login password in the keystring.
If you forget the password and cannot provide the old password to the keystring to reset the user password, you will not be able to access the information in the old keystring and a new blank keystring will be created.
Above is the Mac computer key string password how to update the method, the need of friends welcome reference operation! For more Mac tutorials, check out Mac.orsoon.com