Hi Joan,
Thanks for reaching out to us! Is the issue that you’re totally unable to select JPG when saving, or is it that it keeps defaulting to PNG? Normally Ribbet will default to PNG if you save an image with some transparency (since JPG doesn’t support it), but if you change it back to JPG (in the dropdown on the save screen) it should remember your preference and let you save in JPG format.
Regards – The Ribbet Team