Agree to save your changes, if prompted. You will have to log out and back in again (System Log Out in Ubuntu 8.10; System Quit in Ubuntu 8.04) for the changes to take effect.
TIP If you find the graphical settings get scrambled while configuring multiple monitors, reboot your computer and, at the boot menu, choose the Ubuntu “recovery mode” option (usually the second choice in the list). When a second menu appears, select the xfix option. Then select the resume option to boot normally.
Changing screen backlighting
If you’re using Ubuntu on a notebook computer, you should be able to alter the screen backlighting brightness using the notebook’s standard keyboard combination, as with Windows. If this doesn’t work, rightclick a blank spot on the bar running across the top of the screen and select Add to Panel from the menu that appears. In the list that appears, select Brightness Applet and click the ADD button. This will add a new icon that, when clicked, presents a slider that will let you alter the degree of backlighting.
Screensaver
You can choose a screensaver and adjust the amount of time after which it activates by clicking System Preferences Screensaver.
Sound
You can change the audio volume by clicking the speaker icon at the top-right of the desktop. Double-clicking this icon will bring up the main mixer window where you can control the volume of individual components of the sound system, such as the CD player, or PCM (PCM is the audio output from applications, including media players and the web browser).
NOTE PCM is sometimes referred to as “wave” or “wav” under Windows.
To fully exploit the feature set of your sound card, click the PREFERENCES button in the main mixer window and put a check alongside any controls you’d like to add to the main mixer window (in Ubuntu 8.04, click Edit Preferences). The new slider or control will be added immediately. The precise features offered will depend on the capabilities of your computer’s sound hardware. For example, to add a slider control for surround sound, put a check alongside the relevant checkbox in the list.
24 : Configuring Ubuntu