Do this in the water in the area you are to be detecting, Turn your volume flat out, turn your discrimination knob back to minimum, select discriminate mode, not pinpoint.
Set your threshold so you can just hear it.Turn your sensitivity knob slowly until you start getting false signals, then turn it back until they just stop.Then you are set to detect.Make sure you use slow even sweeps of your coil if you use uneven sweeps you will get false signals.If the threshold goes silent and then returns at a very low tone you have just gone over some iron.On the other hand go over a non ferrous item the signal be obviuos and the threshold will return at a higher tone.You will have to learn the differences in the sound of good targets, eg small aluminium eg alfoil will give a dull signal where as a piece of copper or lead will give high pitched signals.Generally a gold ring will give a low to medium pitched signal.My advise is dig all signals.Some times you will get a good signal and you will start digging then run the detector over the item again and it starts to blank out.This is because it is a deep item and because of its depth the machine could not identify it properly but because you have got nearer to the item and it has been able recognised as being iron it is now blanking it out. Another way of identifying a rubbish item is you will get a good signal but it ends abruptly, almost like the signal has been chopped off.Get yourself a good long handled scoop you will find some of the targets are so deep you will not be able to reach them without one.If you need any more help send me a pm and I will do my best seeya Neilo