To try and help demonstrate, I have attached a couple of screen shots.
the "from_web" file, is a screenshot showing a personal image for John Leslie-Moorby that I want to change.
The "from_software" file is a screenshot showing the same person in builder software - as you can see, no image. This tree was downloaded after the image was added on the site.
FYi, the image was added automatically as a personal photo after I tagged John Leslie-Moorby in a photo in one of the albums I uploaded.
That got it - thanks!
Might I suggest you update your documentation though, because this help article clearly states that I should load the person from the tree and then change the photo there.
Yeah, see there's collaboration between my father and me on building the site, but obviously I have a version of the tree on my machine and he has one on his, so we decided to just make moves and changes on the software and do as much as possible online!
Thanks again though, I can now roll out more photo albums!