Just got three new Dell PCs - one Precision 3660 Tower and two Optiplex 7000 Towers.  Per my orders, all three came with the Dell wireless keyboard and mouse model KM5221W (the box label says KM5221WBKB-US).

On all three, in order to use the normal F1 through F12 keys, I must also hold down the Fn key.

For example, to close a document in Word, hitting only CTRL + F4 does not work.  Instead, I need to do Fn + CTRL + F4.

This is way wrong.

How do I reverse this situation?

According to How-To Geek, there should be an "Fn Lock" option that is the same as holding the Fn key down all the time.  See https://www.howtogeek.com/235351/how-to-choose-whether-your-function-keys-are-f1-f12-keys-or-special-keys/ 

Will this work on my Dell?  How exactly do I try this Fn Lock on my Pcs and this model keyboard?

Thanks.