3D FlipBook - Imported Images are

Thank you for answering my previous question about having one image on 2 pages. Below are links to screenshots how I would like my images to look and how they currently look in 3D flip book. How can I expand the width of the pages so that way the the images on the 2 pages do not appear "squished" looking on the pages?

https://drive.google.com/file/d/1uoCwI-C18v6aLDGbmLDdyaH79rPv3dJu/view?usp=sharing -- the way the image should look https://drive.google.com/file/d/1ok8qaMuP6YMms8HMZXSjXRDxzXkkRhnJ/view?usp=sharing -- how it looks in 3D flip book