It actually sounds as though the screen resolution is set too high, even if you are using a maximum supported setting. Try using a lower setting. Windows has a safeguard whereby if you set a resolution that the computer cannot display, it will automatically revert to the previous setting after a few seconds. If it does look OK, click the option to retain the altered setting.
LG G6 review: Hands-on with LG’s bold, big-screen shot at perfection