I give you a bad news: the image may appear squashed or enlarged in both portrait and landscape, regardless of whether you decide which one to use.
This is because the image you use has a certain ratio of height to width while the devices are all different from each other (thanks to all the manufacturers for not standardizing this, I hope you get an amazing diarrhea ?).
However, as far as I know it is not possible to make this choice in the Designer.
To prevent the image from being distorted, from code you should use this:
https://www.b4x.com/android/forum/t...t-images-without-distortion.86627/post-548417