JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Sorry but that's not possible. You can only change the background color for now as seen on the pdf editor toolbar. Unfortunately, I'm not sure if it's possible to implement this considering the resources and process it would take rendering the image on the PDF but I still have added this as a feature request so our developers can decide if this is possible or not.