If you have uploaded images that appear normal on your desktop but rotate 90° once they are on TIME Sites, then the original metadata of that image is rotated and you will need to fix the orientation outside of TIME Sites.
It is a very well documented issue that Windows auto-corrects orientation so you won't know the image is rotated until you upload the image online. You can follow the steps in this article so you can see if an image is rotated in your folders, and you can use one of these online apps to rotate the image for you to resave and reupload:
It could also be due to the EXIF data on the image. EXIF (Exchangeable Image File Format) data provides supplemental metadata, such as the date, time, camera settings, and image orientation. If an image contains the wrong image orientation EXIF data, or if that data is stripped in the upload process for whatever reason, it will display as rotated.
If it's the EXIF data, you can fix the image orientation by rotating it on whatever image editing software you use back to the original position, re-saving it, and re-uploading it.