https://forums.lenovo.com/t5/Lenovo-B-and-G-Series -Notebooks/G505s-need-a-way-to-have-function-keys- by-default/td-p/1245431

Hi,

to get to UEFI on Windows 8.1, you have to press F12 before Windows starts up. Then you have to navigate through EUFI:

Choose advanced tools and after then it loads BIOS. There, on configuration panel you can see Hotkeys (enabled/disabled) - there is help when you hover over this option.

Basically, enabled sets F1-F12 keys to do new functionality set up by manufaturer - you press the Fx key to do special actions (mute, sound up/down, brightness settings etc.).

Disabled turns this functionality off - you have to press Fn + Fx to do these special actions.