you listen to charlie,he knows what he's talking about.
you can also do what is called 'bench testing' how your detector responds to assorted metals at different settings. take off any jewelry so you don't cause signals yourself. next,using whatever settings on your detector you want to see how it responds,lay the detector down on a table or somewhere where you can pass different metals in front of the coil. try different settings.
things will behave differently that are in the ground because of varying factors such as soil type,moisture levels,corosion,etc. but you will have a better understanding of what settings will pick up or cancel out certain metals. ABOVE ALL- read the instructions and review often. take your time,never hurry and be aware of your surroundings. take care,
bruizr