Sideways photos??

[Pizzabrewer]

How come, almost every time I post a photo in a forum post, it shows up 90-degrees crooked?  For instance,

https://forum.mrmoneymustache.com/off-topic/soft-coated-wheaten-terriers/msg2211276/#msg2211276


In this case, I edited both photos multiple times, reduced the size, re-oriented, etc.  Yet only one of them was I able to make it show in the proper orientation.

????