It is a little tricky to use the Nest as a dumb thermostat, as it's fundamentally designed to operate to a schedule that you program. Go into the schedule (on home.nest.com or in the Nest App or on the device itself) and set up the times and temperatures you want. If you don't always want the same temperature at a particular day and time, you can manually override the schedule but as you noticed that's only temporary -- the Nest reverts to the schedule at its next set point. So, one way to mimic a dumb thermostat is to schedule exactly one set point per day. E.g., every day at 6AM, schedule the Nest to heat to 65. Then, when you get up in the morning, you can twirl the dial to whatever you like, and continue modifying as you wish throughout the day and at bedtime. (Caveat: I haven't tried this myself. I have two set points per day, so it's possible that the Nest won't work with only one, but if so you could schedule your second point to be your normal bedtime time and temperature.)
