Windows 8 & 8.1 Instructions
From the control panel select Appearance and Personalization.
Then click Display.
Now checkmark the Let me choose one scaling level for all my displays (indicated by number 1) and you'll see the DPI size options appear.
Make sure Smaller - 100% is selected (indicated by number 2).
Lastly, if you made any changes, press the Apply button (indicated by number 3). That's it - easy breezy!
Windows 10 Instructions
From the Windows 'Ask me anything' search box, type 'display'.
Click the 'Display Settings' result that appears at the top.
From the Display screen click the Set a custom scaling level* (indicated by orange box and yellow arrow) and you'll see the DPI size options appear.
Make sure 100% is selected.
Lastly, if you made any changes, press the Apply button. And voila!
*If your computer does not initially show the options in the picture, click the Advanced display settings option then scroll down to click on "Advanced sizing of text and other items".