To change the screen resolution of a computer running Windows 7, open the Start menu, click Control Panel, navigate to Appearance and Personalization, and click Adjust Screen Resolution. Go to Resolution, click the drop-down menu adjacent to it, select the resolution you want, and click Apply. When a preview of the new resolution appears, click Keep to use the new resolution. If you prefer your older resolution, click Revert instead.
The procedure is the same for a PC running Windows Vista, except to access the Screen Resolution settings, you must go to Appearance and Navigation, click on Personalization, and then click Display Settings. Alternatively, instead of going through the Control Panel, go to the desktop, right-click a blank area, and select Screen Resolution. This also applies for Windows 8 PCs.
To change the screen resolution of a Mac running OS X Yosemite or Mavericks, open the Apple menu, go to System Preferences, click Displays, and then click Display. Select Scaled, and select one of the resolution options. If you have an additional display connected to the Mac, press Option as you select Scaled to see additional resolutions for the secondary display, and then select a scaled resolution for it. If some apps don't properly fit on the screen afterwards, try out a different scaled resolution or switch back to the original resolution.