Fuel selector
My PA28R had the fuel selector on the left cabin wall, and it was not practical to reach it, or even see it from the right hand seat.
I remember one occasion when a young pilot was doing a checkride, and the inevitable forced landing practise. He changed fuel tanks as part of the procedure, but got the selector in the wrong place.
But he knew exactly what to do when the engine failed to respond to the throttle.
He said "handing over".
True story.