I occasionally use the option when saving an edited picture to just overwrite the original. I would have thought that this option might go further by having the program default of making the saved copy the the same size as the original or if its dimensions had altered save at the same resolution& degree of compression. Did I miss something?
Thanks in advance
No such option exists.
Since the whole point of JPG compression is to represent the photo in fewer bytes by compressing "similar" pixels, of course edited photos will have a different size than the original. I would strongly advise you to abandon the idea of writing an edited JPG to be the same file size as the original, as this idea is not sensible. Don't waste your time trying to achieve this. Instead choose a Quality Level/Compression that you are happy with and use that.