First off, ensure that all of your system's drivers (graphics card, audio card, operating system, etc…) are up-to-date. Out of date drivers can cause issues with various software. More information here: https://www.howtogeek.com/135976/how-to-update-your-graphics-drivers-for-maximum-gaming-performance/
If your game's textures, characters, and environments are blurry or looks like it is being displayed at a lower resolution, disable the Netbook and/or Small Textures Mode for your game.
To do that: on your game's main menu, click on Options, then switch Small Textures or Netbook Mode to "Disabled".
Should the step above does not help, and your HUD, Main Menu screen, Inventory UI are blurry, you may have to go into your AMD Catalyst Control Center (CCC) and override your application mipmap settings to "Quality" over "Performance". For more information on this, see here: Hud elements, Inventory Screen, Main Menu Screen are blurry