On the newer ones one can change it at the thermostat under settings. If I remember correctly, the reason given years ago, is that it was mimicking old dumb tsats where your set point is on top, and their research that indicated if someone felt hot or cold the question they asked was what was the temp set at not what the temp was. In theory the actual temp and set temp should always be within a few degrees. If you use the home app instead of the nest app the room temp is right below the big dial.
