Thanks so much for all the advice!

I asked my husband how HE managed to get such nice warm showers as he
claimed. Apparently I had the routine wrong. I am supposed to crank it
to very hot, and then VERY SLOWLY, in small amounts, nudge it back
colder. If I just crank it back quickly, then it won't work. Does that
sound right to you folks?

It is an electric heater, not gas. Everything here is electric. The
old tank was ancient, and needed to be replaced. It was eating up a
TON of electricity- and never mind the sludge that was probably in the
bottom of that tank! Hahaha-

Anyway I will definitely find a low-flow shower head to put on it. I
just hope that our washing machine and especially the dishwasher is
getting the hot water they need- but, we also replaced the old,
extremely non-efficient units with brand spanking new LG ones. It was
self-defense mostly; we have a well that before simply did not produce
enough water to take care of everything like was needed. Do 2-3 loads
of laundry, a couple showers, and a couple loads of dishes and you're
risking running out of water until morning. Not anymore, though. I'm
banking on the LG efficiency to be o.k. with the Tankless.