Sony VGN-S150 - Manual (Page 204)

Why don't the Fn+F2, Fn+F3, or Fn+F4 key combinations work?
The Fn+F2 keys toggle the headphones and built-in speakers on and off. The Fn+F3 keys decrease the built-in speaker
volume and the Fn+F4 keys increase the built-in speaker volume. The computer may not recognize the Fn+F2, Fn+F3, and
Fn+F4 keys if the correct speakers are not selected. Follow these steps:
1. Right-click the Volume icon on the taskbar, and select Adjust Audio Properties.
2. On the Volume tab, click Advanced in the Speaker settings box. The Advanced Audio Properties window
appears.
3. On the Speakers tab, select the correct speaker setup from the Speaker setup drop-down menu.
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