Edits Saving wrong

[PaulM]

Hi all, 

I'm new here. I've tried searching for this but can't find it. My edits are coming out all wrong. The colours aren't correct, if I crop the changes are in the wrong place. 2 edits in one image (with only one save) goes all wrong. I've attached 3 images to try to explain it. 

Using GIMP 3.06

Thanks,
Paul

1. an image I made (Untitled.jpg)
2. a screen shot from gimp (Chng1.jpg)
3. the output file (Chngd.jpg)