Drive to Average will adjust the night setpoints so as to maintain an overall daily average target temperature.

Here is a Video:

To program hit Enter/Menu-> then highlight Setpoints Advance hit Enter/Menu -> then highlight Drive To Average and hit Enter/Menu.

Selecting Drive to Average brings you to the following screen

The Drive to Average option can be either Enabled or Disabled. Enabling it engages the option.
The Target Temp is the average temperature you are trying to achieve.
The Max Fail Days is the number of successive days that the target temperature cannot be achieved after which adjustments are made automatically to the day setpoints.

The Allowable Target Deviation is the number of degrees that the average temperature is allowed to vary from the setpoint before a fail day is signified.
The Max Adjustment Size is the maximum number of degrees by which a setpoint adjustment can be made.

Here is a view of Setpoint Advance Influence Factors Programming with LinkConn 1800 Software which provides a more simpler control view.