Why do my pics always show up sideways?
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Why do my pics always show up sideways?
This is helpful
Why your photos show up sideways on SMC
I would suggest using the "Go Advanced" mode where you can preview your post before it is actually posted. I straightened your photos by simply opening them in Microsoft Photos, rotate them as need then click on the Attachment 516864 and make a very slight height or width adjustment and then save the file. They will then save in the upright orientation.
Also you can edit a post anytime during the first 24 hours it has been posted. This would allow you to fix photos that display improperly. You can also delete a duplicate post during that time frame. Or simply ask a moderator to help.