PayPal form is showing wrong thank you page

I have used an art submission form a number of times by cloning it. The problem is that I can't update the thank you message.

For what is now the Pope Up submission form, I have been able to make the changes I needed on the form itself, but when I went to change the thank you message, it apparently has not changed. People submitting get the message we sent out for an earlier show which says "Thank you for submitting to Art Between the Covers." 

How can I fix this?

Thank you for contacting us.

I have submitted the form (bypassing the PayPal field), and I saw the correct Thank You message.

If the form is submitted with the PayPal payment, user is usually needs to click on the return link (unless the PayPal Auto Return is enabled for your PayPal account) to get redirected to the Thank You page.

If the issue still persists, please let us know.