[Q] Lollipop navigation buttons topic

Hi - I added a 2nd user and my games open in the new user without hiding the navigation buttons. How do I force a game to open without hiding the navigation buttons on my primary user?

Phone Motorola Moto G 2nd Gen
Apex Launcher
Android 5.0.2

Hide navigation keys topic

I own the D838 Hong Kong version which came with the 10F software and I have now installed the 20C kdz. Everything works great and I'm loving the device as expected (second one that I have owned) however, on my previously owned LG G2 and LG G3's there was a software implementation from LG which enabled the ability to hide the navigation keys automatically in any app that the user wanted.
Could anybody tell me if this implementation is available in any of the custom roms for this device, or indeed, any of the stock roms which are available for other variants of this device?
It is a fantastic feature which I would really love to have on my G2 Pro to fully utilise the gorgeous, massive screen. :D