Sometimes photos, even if they look correct on your computer, will upload to Exposure rotated 90°.

On your system, it looks like this:

On Exposure, it uploads like this:

Or even smooshed (note from above that this image should be taller than it is wide):

The root-cause of this is that some cameras and phones do not save photo orientation in a way that Exposure can recognize as the instructions about the photo.

To solve this, open the photo in your operating system's preview app (or your favorite photo editing app), rotate the photo to the desired orientation, and re-save or export the photo...even if the photo already looks right-side up in your photo editing and/or preview application.

Yes this is silly, but it works.

The re-saved, re-rotated photo should now upload correctly.