Thank you for reaching out to us. Unfortunately, as this time we are unable to edit the landing page that thanks people for signing up. I would recommend checking for an app on our Marketplace which may be able to do what you need!
This is hard to believe. What if "Thank you for signing up" does not fit my purpose? That is, the form is not signing up anybody, it simply collects an email to send a link to.
I can understand why you would want to change the success message on the sign-up form. As Briody mentioned earlier, we suggest visiting our Marketplace for third party sign-up tool that may have more of the editing ability that you are looking for.
We will certainly take down your feedback about our sign-up tools and forward it to the appropriate team.
Please feel free to reach out to us with any other questions.