How do you correct them? Some say glue them down or add more screws. Recently I watched a video by The build show host Matt Risinger where they used spray foam on the underside of the staircase to lock everything in place. The squeak comes from the wood rubbing togethor and/or the nails/screws rubbing up against the wood when weight is applied. In this case the stairs were removed and the failed glue removed. We replaced it with thick carpet under-pad felt between the wood. This way the only rubbing that can occur is the screws in the wood. So far no squeaks. Only 20 years down the line until we know if this method truly did the trick...🧐