Don't know if this issue got solved for you when you posted it, but if not normal solutions from easiest to more expensive (though none are real expensive - probably not more than $1000 for most expensive). I am assuming you have only one thermostat for the two floors, because if there is a separate upstairs thermostat just turn it down till you get the desired temp up there.
0) if new home, contact the builder under warranty to have it fixed, which might include doing one of the more expensive (last) choices.
1) put in (if not there already) adjustable hot air supply vents upstairs to limit the airflow up there - meaning it will heat less quickly and you can adjust the room vents so each room comes to roughly the desired temp as the thermostat turns the furnace off. Easy to DIY (just a couple of screws each) and $15-25 each at home improvement/box store depending on size and whether metal or not. You should not shut off the flow at any vent more than about 50%.
2) if there is a door between ground and upper floor, try closing it - might be you are heating the upstairs with direct air flowing up there PLUS heat rising from first floor
3) commonly this second-story problem is due to one thermostat covering two floors - sometimes moving the thermostat to a more representative or "avearage" location works, especially if it is being affected by a nearby large window or drafts from a door or stairway
The following ones depend on duct routing - with furnace located on the second floor (unusual location for new construction) might be isolating the upstairs from downstairs will not be simple.
4) install a manual damper in the ducting leading to the upstairs, setting it to reduce the amount of air going up there. See 5) below about checking what this is doing to the furnace/blower fan.
5) put second thermostat upstairs, and an electric controlled damper on the upstairs main feed duct, so the thermostat shuts off the airflow to the upstairs once the upstairs reaches desired temp - with the airflow still going to the downstairs until that thermostat is satisfied. This should be done by an HVAC tech, who should check that this will not be too much restriction on the airflow from the furnace and is not creating too much back pressure on the blower fan.
6) redo duct sizes to increase the airflow to the downstairs - I suspect undersized ducting for that longer run is the source of the problem - like the contractor did not do a proper ACCA Manual calculation of the heating load in each area (taking into account the insulation differences) and proper sizing of the ducting and vents.
7) I wonder about the spray foam insulation - why, on current new construction, was it done on only one floor ? Normally, to achieve a good energy rating and energy efficiency, if it was used on one floor it would be used through the house. The question would be how good the insulation downstairs is (if any ?). Maybe you did not get the energy efficiency you paid for in the new house ? This is not too uncommon - insulation contractors skipping entire walls or floors or attic because of miscommunciation or because the inspector and homeowner are gone so they take an opportunity to save money by skipping part of the job - especially with blown-in and foam-in-place injected (as opposed to sprayed in before the drywall) insulation if they can get the drywall holes patched up before anyone notices the lack of insulation in the walls.
