How to activate function lock key on Pavilion AiO

[DeRochier]

How do I activate and de-activate the function lock key on the keyboard that came with my Pavilion AiO? The only instructions I've found involve going into the BIOS settings. Somehow I've been activating it via the keyboard but I don't know how I do it. For example, yesterday when using Microsoft Outlook, pressing the F9 key (by itself) would activate send/receive. Today pressing F9 activates the Print command and instead I have to press FN +  F9 to activate send/receive. A similar thing happened in Excel: yesterday pressing the F4 key (by itself) would create an absolute cell reference. Today I have to press FN + F4 to do that same task. I appear to be activating a function lock at certain times but don't know how I'm doing it.

[erico]

Enter the BIOS and check for an action keys enable/disable option.

Enable the Action keys and you have set the function lock.

Disable leaves only the function keys enabled, requiring the press of the Fn key to use the option (if one is present) on the Function key.

Don't forget to save the change before exiting the BIOS.

[DeRochier]

I understand you can change the action key settings in the BIOS, but somehow the action keys are being toggled on/off via something I'm doing on my keyboard because they're toggling on/off independent of the BIOS settings. It appears there's a key or combination of keys that toggles the function lock on/off. I'm trying to find out what it is without resorting to going into the BIOS settings.