Some photos taken with iPhones (and maybe other devices?), and uploaded to forums are rotated on their sides when displayed in a browser.
At this point, the only solution is to download to your computer, orient and save to a new file with graphics software before uploading.
Investigation reveals fixes are not easy on the forum management end.
When a photo is taken with an iPhone, Exif data is applied to the photo file which the iPhone then uses to display it correctly in whichever orientation the iPhone is held. Rotate the iPhone, the image stays upright. But when that photo file is uploaded to most discussion forums, the photo is often displayed on its side.
Moderator forums are full of problem descriptions and suggested fixes, but also problems with those fixes - they are not consistently reliable. Until forum software or an auto-rotate extension reliably deals with the problem, we are not inclined to test beta type code bandages, which in our experience causes further problems. A fix will come along.