用户keychain上保存的还是就的验证密码，但是用户已用新密码登陆系统一个多月了，也不记得旧密码，因此某些app启动时会要求输入keychan的密码。因此只能重建keychain了。

* Close all applications and choose Go to Folder from the Go menu in the Finder-> Library

* Enter this path:  ~/Library/Keychains

* Select all items in this Keychain folder and drag them to the Trash.

* Restart the computer immediately.  After the user logs back in, a new login keychain should have been created.  You can verify this by opening Keychain Access (in the Utilities folder in the Applications folder), and checking to see that there‘s a keychain named login in the source list.  It should be unlocked automatically when the user logs in.

Mac OS创建新的Keychain