How To Change DPI (Dots-Per-Inch) In Windows 7/Vista
Type DpiScaling in start menu search box or run and press Enter.
Select your desired DPI. If you want to set a custom DPI, click Set custom text size (DPI) in the left-side pane.
Click Log off now.
Now your PC will log off and all the things will be enlarged or reduced according to your DPI.