04-21-2017, 06:23 AM
As Blighty says. File>Save is only for the XCF format that saves all you work (added layers, selections, paths...). To produce "display" formats such as JPEG/GIF/PNG use File>Export. When you leave Gimp or try to close an image that you didn't save as XCF, Gimp will ask you to confirm. This is a bit painful at teh beginning, but 1) you can get the Ctr-lD reflex. and 2) you will be glad you have this when you start doing complex things with Gimp.