How do you change the resolution in paint (dots per inch) in microsoft?

My computer says the resolution is 81x81 dots per inch but I would like to change it to 72 dpi. Anyone know how?How do you change the resolution in paint (dots per inch) in microsoft?
You can always change the size of the picture by going to Image-Attributes (or Ctrl+E) and making it 72 x 72 (or whatever you need it to be), but doing this crops the picture. If you need to resize it so that it becomes 72 x 72, go to Image-Stretch/Skew (or Ctrl+W) and use 88 in the horizontal and vertical box.