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 10.

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 Display settings.

Select the display you like to change the resolution to the native resolution of the monitor.

Change the Desktop Area (or Screen area on some PCs) to set the resolution (example 3840 x 2160).
 

If you still have problems it please contact ViewSonic Customer Support.