where do I increase the dpi value of a saved jpg.
Sorry, not exactly sure of whay you want to do.
But if I wanted to open an image at a specified ppi, I could open CUSTOM, put a dot in use original size, and set the over ride to 300ppi
The other thing I could do is use Print to File and in there set my ppi and image size to whatever I wanted.
See screen snaps
Another option, if you don't mind some arithmetic, would be to use the CONVERT screen, See bottom of screen snap)
You can see the resolution in the bottom boxes. If my print resolution is 150 and I want 300, increase the resolution in one box to double. Then make a new JPG.
Hope some of this helps.
Fred