I had to delete and reinstall paint.net after windows crash
two things worked in original version.....everything opened to jpg versus jfif type file (pfif is new to me)
I am currently opening, modifying picture, having to "save as" to jpg file
I prefer jpg
previously I could "move" a file or range of files from source to any external hard drive or dropbox
now, I can only find "copy" to another hard drive, then delete the copied files from source drive
apparently I am now windows ignorant....I tried to set defaults and all it did was create new default apps "photo" and "paint.net"