The image in the receipt is the same as the image you chose for your donation form. To edit the image, go back to EDIT DONATION FORM. To edit the text in a receipt, go back to EDIT DONATION FORM and click on the “ADD RECEIPT DESCRIPTION” field and ...
Go to MORE OPTIONS > CUSTOMER INFORMATION and click on the box next to “ADD CUSTOM FIELD FORM”. In the field underneath the box, type whatever text you’d like displayed on the form.