In Base, how do you insert a form field on top of an image?

I converted a pdf form to an image and imported it to a database form. I’d like to add fields on top of the image but it won’t let me. I’ve tried sending the image to the back. Any ideas?

This is working for me when I go: Insert → Image → From file. By default the controls (e.g. text box) is on the top and visible when I run the form.

Which bit wont it let you do? I found that if the image is on top of the text box, then I cannot select the text box. But if I send to back, then the text box is selectable in the design view.

Set the image as the background for your form document.
Right mouse button click anywhere on your form page that is free of any other object.
Choose Page from the context menu.
Click on the Background tab.
Select Image in the dropdown menu. Position as desired. Apply (OK).