Recently installed a noma programmable thermostat and same was working fine for three or four days but this morning the furnace kept running. Temp was set @67F but furnace was still running @ 79+F .The only way to stop the furnace was to manually shut it done.Why is it doing this and what must I do to correct it?

Toss the Noma thermostat they are junk. Get a Honeywell instead.