We don’t support adding the confirmation message while displaying the form (again) though it’s a feature we might add in the future because I do agree in some use cases it’s helpful.
For now the way to do it would be to create a “Thank You” type page with your desired text (Thanks for contact us yada yada) and then after that just insert the form with the shortcode. Lastly, in the form confirmation settings, change the setting from using a confirmation message to sending users to the Thank You page you created.
Hope that helps!
