It isn't changing the picture at all. You uploaded a full-rez pic and didn't give it a size so it is displaying it full size. To resize: after uploading (still in the editor) select the pic then click the Insert/Edit an Image button just to the right of the upload button. Set the width to something reasonable for viewing, like 500-600 wide. I just did that to your pic. Notice if you right-click on it - open in a new window/tab - you'll get the image full-size.
The old site would rip uploaded pictures down to about 600x600 automatically, but that would take away clarity/readability of certain things with no way to make it better, so this time I just left the power in the hand of the member. I'll probably have to put some kind of restraint on it, I see.