How do you limit to one unique question per day?

how do you limit to one unique question per day?

If I understood you correctly, you want to receive only one submission per day. That is unfortunately not possible.

However, you can restrict submissions per user: https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form

You can also set a submission limit based on a date and/or submission count: https://www.jotform.com/help/137-How-to-Limit-Submissions-in-a-Form