If the heat level in your house exceeds the set temperature on the thermostat, there are two likely causes. The first is that the thermostat may be mounted on the wall crookedly. An examination of the Thermostat should let you know if this is the case.
If the Thermostat appears to be hanging on the wall, crooked, remove the cover, loosen the screws that are holding the Thermostat to the wall and then adjust the Thermostat so that it is level. Tighten down the screws that hold it in place and replace the cover. Test it again and observe if the temperature is still getting to high.
If this is not the culprit it could be that the Thermostat heat anticipator needs to be recalibrated. You should find this anticipator in the center of the Thermostat. This device tells the furnace at which point it should turn off. This can be technical so we advise you bring in your licensed professional to make the adjustments.