Not having the fan model numbers, I can only give the 2 most frequent locations.
1. On top of the fan, you drop the light kit down and then the , there may be a cap that slides down the rod and sits on top of the fan.
Lifting the cap up exposes the switches
2. The second most often, is where the light kit attaches to the fan, you drop the light kit down and then the receiver is right there between the light kit and the fan housing.
If in neither location , need the model number of the fans.
Before even doing all that, do as I suggested and only have one bulb in the light kit if it has more than one and be sure it is low wattage, then test the lights again.
If the problem is the wattage limiters because some used too big of bulbs at some point, then they may either work with one lamp or have failed completely.
The other key which I have asked, is DO THE FANS WORK?