@Bandit When you upload a picture from your phone, CoSo, as a security measure, strips all the metadata so that no one can see your location. Part of that means that your pictures are sideways. You can either a) take pictures landscape, or b) make a minor edit, save, then upload, and it'll be fine.
@Bandit And this is JUST for uploading pictures from your phone. If you're posting pictures on your computer, this isn't an issue.