How can I make sure all questions must be answered

I have another question: How can I make sure all questions must be answered

There is an option to set the fields as 'required' on a form. This would help to make all answers mandatory. 

To set a field as required, please right click on it and select 'Require'.

We will be glad to assist if you need more help, just let us know. 

I figured it out. Thank you.
How do I make my form only one page instead of multiple pages?
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To make the form one-page, please delete the page breaks, like this: