Set the resolution higher.

Test the monitor on a different computer to isolate the problem.
Please follow the instructions below on how to change the resolution on a computer running Windows.

Changing the Resolution for Windows:
Resolution is a setting made through the computer being used with the monitor. 

The display takes in the resolution from the computer and if it falls within the monitor's working range, an image will display. 

Setting and checking the resolution is done through the computer's operating system, and what determines the resolution is the video card.

To change the resolution in Windows, do the following:
Right-click on an empty area of the Windows® desktop. From the pop-up menu, select Properties, then select the Settings tab. 

Change the Desktop Area (or Screen area on some PCs) to set the resolution (example 1280 x 1024).
For the clearest and sharpest image it is best to select the displays native resolution. Check the specs of the display for information of this setting.