Faststone resizer problem

[sldi-rooster]

I searched thru the forum for info on this but didn't find any help. I was attempting to use Faststone to add a border and watermark on some photos. On photos that I had previously shrunk the file size down for the web it would increase there size with the border and watermark added, but when I tried the full size files it is shrinking the file size down by an average of 67% although the dimensions are staying the same, I know I must be losing quality in this. I have unchecked the resize box on the batch convert and use all the same settings whether it is the previously shrunk files or the originals. What have I not set right or is this just the nature of the program?