Change default sound theme to custom one
1. Open the Control Panel by clicking on the Control Panel tile on the Start Screen.
2. A control panel Window opens. Scroll down and click on the More Settings.
3. Click on the Hardware and Sound.
4. Next, Click on change system sounds.
5. Next, you can change sound in this window. Select Sound Scheme from dropdown list or use your own sound by clicking Browse and select the sound. Set the Program Events when you want to play the sound in the Program Events section. After you are done, click on the Apply button and then OK. That are the complete steps to change sounds in Windows 8.