K let’s say you have an AMD type video card, open Catalyst Control Center (start typing that in the windows start menu search) and open it up. Open the Gaming tab and click 3D application settings and scroll down to Catalyst A.I. and move the scrollbar for Texture Quality all the way to the right. Same with Mipmap detail level under that.
Nvidia probably has a similar setup but just
External Media
P.S. The reason the guis are blurry in the first place is probably because your settings lower the quality on the larger sprite sheets for the buttons and other images