Thanks for the tips guys, these suggestions have given some ideas to try. Like entering the text directly into PaintNet, saving a master copy of the result as png then convert to jpg later. Excellent suggestion, didn't know Png could do this. Will definitely download PngGauntlet. Did try Metadata but black interface is not so good for me to see.
I opened a jpg photo in PaintNet, added a name and saved as Png file size 493k. Opened into PhotoRar and it suggested 18k which was still very good. I turned the compression down to 7% and it gave 72k.
Then I got the idea to open the photo/with/name I had saved in Paint.Net as png and told it to save as jpg. Then saving with default clicked, the result was very good and only a 20k difference from PhotoRar.
I especially like the fact that PaintNet shows the results while choosing a compression, and also shows the file size while using the slider. Well done. I think I am going to being using PaintNet a LOT.
The only suggestion I have to make it better, when typing in a name on a photo, capital letters like "A" and "S" are quite a bit stairsteppy. It is noticeable only on extreme zooming in higher than 200% so isn't really an issue. However I did check the same letters in Word and they were very smooth. So I tried copy and paste to PaintNet and it wasn't as clear as word. Tried anti-alias and the smooth/sharp, it's ok.
Other than this, I am really glad I discovered this terrific program. And with users stwpping up to help makes it even better.
Thanks again Everyone!