Oh, boy! Do you have any idea how reluctant old geezers are to change? You might as well ask them to learn how to use Windows 8.
Oh, I know. Number one, I'm using Mac OS 9.2.2 on a nearly 20 year old PowerMac 7600 (souped up). Number two, Windows 10 is an awful lot like 7, in that it dumps that stupid dual-menu crap pushed down everyone's throats in W8. I mean, really, a dual level menu? I remember that from 30+ years ago, the Zardax word processor on the Apple II.