How do I add a question (custom question?) field to registration form for webinar.

Hi, 
We've been using Zoom for a few years now, but we want to add another required question field to our webinar registration. We can't seem to figure out how to accomplish this. We've found this (see below) but cannot seem to locate the Questions and/or Custom Questions tabs anywhere. Any help would be appreciated. I've attached a screenshot to demonstrate what and where I'm talking about. Thanks! 

Custom Questions tab

Note: When the host or webinar organizer edits or changes the registration fields under the Questions and Custom Questions tabs, registrants are required to re-register before attending the webinar.

1. In the Registration window, click the Custom Questions tab to add questions to your registration page.
2. Click New Question to add a question.
3. Choose the type of question: Short answer, Single answer, or Multiple answers.
4. Check whether the question is required.
5. Enter the question.
6. For single answer or multiple answer questions, enter the answer options.
7. Click Create. Repeat the above steps to create more custom questions.
8. Click Save All to save your customized registration.