If you forget an app or server password
If you forget a password that has been stored in the keychain, you can have Keychain Access display it for you.
By default, the keychain password is the same as your computer login password.
Important: Don’t forget the login password for your computer. If you do, you won’t be able to view any of your other passwords in Keychain Access. See If you’re asked frequently to unlock your keychain.
Select a keychain.
Click Passwords in the category list.
Double-click a keychain item.
Select the “Show password” checkbox.
Enter your keychain password.
To display your password, click Allow.