Ticket: User Preferences, passes but can't find Preferences field in Users collection

I’ve got the correct answer to this ticket and can see the detailed answer, but when I tested it using an account I set up, the Preferences will never be stored in the Users collection. Every time I log out and log in, the Preference will be blank. I use db.users.find({ name:***), can’t find the Preferences field added.

I copied and pasted the official answer, then npm start, and refresh the website, still not working.

Any ideas?