In the “guide to creating a signup form” the pop up is customised with that coffee bean image. It says to use a 600 x 500 image approx. https://help.klaviyo.com/hc/en-us/articles/360026474752-Guide-to-Creating-a-Signup-Form
So how do you add this image at the top of the form in the options? It does not explain this in the article!
The only form edit options I see are form type, side image, form background and form styles. So where is the option to upload a header image to the form?