Instructions
Open "World of Warcraft" by pressing "Play" on the game launcher.
Press the "Options" button in the bottom right-hand corner of the Account Login screen. Select the "Graphics" page in the upper left-hand corner of the options window.
Locate the "Resolution" option beneath the "Display" tab at the top of the window. Click on the arrow to open a drop-down menu with all available resolutions.
Hover your cursor over the "1280x960" option and left-click to select it.
Press the "Apply" button in the lower left-hand corner of the screen. Press the "Okay" button to close the options menu.