Can't make Function Keys default to Media

My function keys used to default to media, that is to say each Function key would control something like volume or brightness, etc. But since some new updates to my XPS 15 9560 those keys now have other functions and to use them to control things like volume I now have to hold down the Fn key when pressing the corresponding Function button. I would like them to control the media functions by default, as they used to do. 

I did my online research to solve the problem and already tried the following three solutions:

• Hitting the Esc key (Fn lock) and the Fn key at the same time. 
• Changing it in the Windows Mobility Center (there was no option there, see photo attached)
• Entering my bios to change it there (Again, there was no option there, see photo attached - I looked into each of the submenu options)

None of these worked. Does anyone else have an idea to share? I would greatly appreciate it. Thank you.