I recently purchased A Phantom 3 professional, I hear of several horror stories of flying over water.  What are the setting I should be using when flying over water .I would like to keep this thing as safe as I possibly can, any feadback would be greatly appretiated!

remember that VPS does not work well over water, so if you are flying in atti mode be careful. if inp-gps then u r pretty safe as i have found mine to be rock solid. and i dont turn off vps as suggested by some, but u could since it does not work well above water anyways. and after, i cant remember, so many feet VPS does  ot work any ways.
apart from that there is not much settings you can change