After editing a photograph I've saved it to my folder on my desktop, but when opening the file again all my edits are missing! How do I save my edited files?
How did you save it? In Gimp 2.8 "File/Save" is only to the full-fledged Gimp format, so if you "Saved" a JPG after editing it's in an XCF file somewhere (likely easy to find: "File/Open recent..."). To "save" to non-Gimp formats (including the original file if not an XCF) you have to use "File/Export".
It can't be. What is the software are you using to edit the picture? Save them in .jpg , .png or . jpeg formats.