Problem solved!!
To select the watch face you want for any Focus, such as Sleep Focus, go to Settings>Focus>Sleep and under Customize Screens, choose the watch face you want for that Focus mode. (This is what doogald said to do above.) BUT, you also have to click on Options beneath the Customize Screens and TURN OFF Sleep Screen. If you don't turn that off, the phone ignores your customized selections and instead uses the defaults.
By the way, the free 30 minute session with an Apple Specialist was a complete waste of time. The specialist had no idea what I was talking about. Their role is to ask you survey questions and then guide you through any VERY basic things you don't know such as how to take a picture. I'm going to boldly assert I know more about the iPhone and the Apple Watch than that dude. The only useful thing he suggested was calling Apple Care. The Apple Care service agent I spoke with figured out the solution in just a few minutes.