How to change iframe height of thank you page on submit?

Currently when submitting the form the height of the iframe stays at the height of the form after submitting.  This causes a lot of  white space below the message.  Is there any way to adjust the height of the iframe after form submit and scroll down to the section showing the thank you message? 

Unfortunately its not possible to change iframe height on form submit however you can customise the thank you page to fill the page:

https://www.jotform.com/help/211-Setting-up-the-Thank-You-Page

https://www.jotform.com/help/51-How-to-Post-Submission-Data-to-Thank-You-Page

Alternatively you can redirect your thank you page to a custom url  and you can customise this thank you page.

https://www.jotform.com/help/38-Redirecting-Users-to-a-Different-Page

https://www.jotform.com/help/89-Create-a-Custom-Thank-you-page-with-Auto-redirect