This is a font issue. If you do not run recommended resolutions (i.e. 3:4 on a 16:9 monitor), the applications' menu become blurry under Windows 10. You can run a tool in the display settings somewhere to calibrate it manually, but that does not guarantee it works for user interfaces of all applications.
To change the resolution, right click somewhere on the desktop and choose Display Settings. Then choose the resolution from the dropdown menu in the new window.
And you need to logoff/on again to apply font changes.