39 Ω or 47 Ω is not really relevant. YOu'd have to choose a really larger value, e.g. 150 Ω, to get a marked change in power dissipation. Obviously the power rating was insufficient.
Better use a 1 W resistor for some safety margin. Or use 2 or 3 times 47 Ω in series, each 1/2 W rated, toi distribute the power dissipation.
Note that without knowing the load details this can be only a rather general recommendation.
You work at your onw risk. Observe all necessary safety precautions to prevent any injury due to electric shock, fire from overheating etc.
This forum and its mambers can and will not take any responsibility for damages due to your design.