I have 2 forced air gas heating sytems. 1 is in the basement and has a contoller on the first floor and the other is in the attic with a controller in one of the bedrooms on the second floor. I have been told that there is a offset (+/-? Degrees) in the settings between the 2 controllers (e.g.-upstairs 2 degress warmer than downstairs or vice versa) that will optimize the heating efficiency but I can't remember the rule. Anyone have a suggestion? Thanks for your time.

Never heard of that rule. The only rule is to keep the thermostats turned down as low as possible to keep from burning fuel while maintaining your personal comfort level.

What should I set the thermostat to heat the house

At whatever temperature you are comfortable at and can afford.

I have a weird system in my house I have a downstairs thermostat and an upstairs thermostat with 2 dampers and a zone control board... my main thermostat witch is down downstairs is set to reverse valve off or "b" my slave witch is up stairs is set to reverse valve on... my dip switches on my zone control are set to heat pump with reverse valve... it took me hours of changing settings and switches I have a ruud heat pump package unit works real well.. with smart stat digital thermostats... with an xci controller