What lights are flickering? Just the fan light fixture (look for a loose connection) or the entire circuit?

The four lights on the botom. I bought two Identical fans at the same time and they are both doing it. I have put up this kind of fan before, 22 of them to be exact and I have never had this happen. I have checked the connections and found no problems. I then changed the light switches and the new switches are buzzing.