Instructions
Click the "Start" button, which is located on the left side of your taskbar.
Click "Programs," followed by "Ragnarok Online" and then "Setup." The setup program opens.
Click the box next to "Full Screen Mode" if you would like the game to display full-screen on your monitor. If the box is not clicked, the game will be displayed in a window.
Set your resolution from the drop-down menu below the "Full Screen Mode" box. Select the resolution that corresponds to your monitor's native resolution for optimal performance.
Click "OK" when you are finished to save your "Ragnarok Online" monitor settings.