How to prevent multiple submissions?

If you mean to ask how to prevent multiple submissions, then I would suggest several options:

1. Setting unique submissions on your form: https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form

2. Setting form limits based on a unique question: https://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question

3. Adding a captcha field to your form: https://www.jotform.com/help/205-How-to-Add-a-Captcha-Field

I hope this helps. If you need further assistance please let us know. Thank you.