Password Popups on Macs after Changing Passwords

If you've recently updated your primary password on your Mac, you will begin seeing prompts to access shared drives and wifi - among other things.

You can get rid of this by updating the keychain password. The keychain stores credentials for resources only you should have access to.

If you know your old password:

Go to Applications > Keychain Access
From the list of keychains in the left side of the window, select "login."
From the Edit menu on the top menu bar, select "Change Password for Keychain Login"
Enter the old password of your user account in the Current Password field. (The password you were using prior to changing it.)
Enter the new password of your user account in the New Password field. (The password you're using now, to login to your Mac.)
Re-enter the New Password in the Verify field.
Click OK when finished, close the keychain window.

That's it!