Windows has become an operating system that is almost synonymous with the PC. While the goal has always been to streamline operations, be more user-friendly and run more efficiently, glitches seem to arise whenever dealing with anything computer-related. One such glitch is the operating window becoming a size that doesn't properly fit the screen. This can be fixed in several different ways.
If everything is working properly, use your mouse to fix the window size and adjust as needed. First, drag your mouse icon to the upper right of the window. Next to the "X" icon that closes the window is an icon with either two squares on top of each other or one large square by itself. Clicking on it should resize the window by either shrinking it or expanding it to fit the screen. If the window is not already fully expanded, take your mouse to any side of the window to the edge. The mouse icon should become a double-arrow. Drag the side of the window back and forth to set the size to your preferred dimensions. If you bring the mouse to any corner of the window, its icon will become a four-way arrow. You can then adjust the height and the width simultaneously.
If the mouse options are not working, try your keyboard. Holding down the "Alt" key and hitting the spacebar should bring up a menu. Use the arrow keys to highlight "Size" in the menu and hit "Enter" to turn your cursor into the four-sided arrow. Hit the arrow key corresponding to the side of your window that needs resizing. The cursor will jump to that side of the window, even if it is off screen. Use the arrows to then resize the window to your specifications.
Another option is to change the default settings for the window itself. Click on the "Start" button in the lower left corner of the screen to bring up the menu. Click on "Control Panel" icon and then double-click on "Display." Once that window comes up, click on the "Settings" tab and then use your slider tab to adjust the resolution and window size. Finally, click on "Apply" once you're happy with the settings to make the changes permanent.