Password not accepted when setting Apple ID in Users & Groups

Problem

When you go to the Users & Groups section in System Preferences and click the “Set…” button next to Apple ID, it asks you for your current password. You do not have a password set and when you click OK it says “You entered password incorrectly”.

Solution

1. If you still have it up, click Cancel on the prompt asking for your password.
2. In the bottom left of the Users & Groups window, click the padlock to unlock it.
   
3. You will be asked for your password. Click OK.
4. Now click the “Set…” button next to Apple ID and you should be able to continue.