Can't quite feel it over a computer. You'll need to have it physically inspected by a mechanic. Knocking while turning is commonly caused by binding upper strut mounts. You can make that noise occur without running the engine but it will be hard to turn the steering wheel without power steering. That isn't serious in itself although it can be irritating. Knocking outside the engine with it running could be caused by the belt and pulleys if an engine mount is collapsed allowing one end of the engine to sit too low. The engine rocks and shifts position in reverse so some things could hit in reverse and not in drive or park. Someone is going to have to actually look at it with the engine running to see what is causing the noise. It could even be something as minor as a broken exhaust pipe hanger letting the pipe hit the floor of the car.