After Paypal has successfully processed sandbox payment the user gets a blank screen,

On my form "Conference Registration" form after completing the form and submitting it then Paypal processing begins. At the end of a successful payment process and clicking "Return to Merchant" the user is taken to a blank page with this url: https://submit.jotform.us/complete.php?sid=3825498222739859469

How can I send the user to a web page that I designate?

How can I send the user to a web page that I designate?

Please check the Thank You section of your form.

There is an option to assign a default Thank You page or a Redirect to external link.

To redirect to a web page you designate simply put the URL of the website in the Redirect URL option.

Ex:

Thank you for the quick response!