Not all apps might be displaying blurred text in which case you can make a small change to fix it on a per-app basis. Right-click the problematic app's icon and select 'Properties'. Go to the 'Compatibility' tab and under the Settings section, check the 'Disable display scaling on high DPI settings'. Click 'Apply' and it should solve the problem.
To fix blurred text that is consistent in all apps, pen the Settings app and go to the System group of settings. In the Display tab you will see a slider that lets you change the size of text, apps, and other items so that they look better on your screen. The safest bet is to set it to zero. If you're using a high resolution monitor though, this might render the text really tiny so try playing with this slider until you find what works best. After each change made to this value, you will need to log out and log in again. Needless to say, a little trial and error will be involved until you get it right.