If you're working at your PC and you want to step away from your machine but don't want prying eyes to see what you're working on, then a screen saver is the ideal time-saver. It stops you having to close down every window before you leave your desk. Here's how to change a screen saver in Windows 7.
From the Start Menu, select Control Panel.
Click on Appearance and Personalization, and from the options displayed under Personalization, select Change Screen Saver.
Using the drop down menu located under Screen Saver, choose one of the default images to have displayed when your PC is idle. You can also elect to have random images from your Photo Library or Windows Live Photo Gallery displayed on your screen instead.
If you select the Windows Live Photo Gallery option, press Settings and you can opt to display only photos with certain descriptive tags, ratings or change the location where images are taken from and even how fast or slow they're displayed. Meanwhile the Photo Libray settings only offer you the chance to adjust the slide show speed, the location images are taken from and whether they appear in a random order or not. The 3D Text screen saver also offers customisable settings. You can change what the text reads, the font and the colour along with the speed it scrolls across the screen at. It's worth noting that none of the other Windows 7 default screen savers have adjustable settings.
Use the Wait box to adjust how long the PC should be left idle for before the screen saver begins. You can also preview how your screen saver will look before you save the changes. If you're happy with the way it looks then press Apply followed by OK to close the window.