More likely to be R64 on the diagram as it matches the 33K value measured on the board but there is obviously some difference between the circuit diagram we have access to and the actual unit as the resistor we are changing seems to be labelled R52. You are correct in saying that R52 on the diagram would not change DVDD as that is concerned with transient response of the circuit.
The pins SET0 to SET3 look as thought they give some software selectable voltages but the highest resistor value there is 36K so that is not of great use unfortunately.