I have one, only used twice last fall.
I can't help with settings as I am still very green to this unit.
Go to Walleye Central web site, and ask there.
You don't even have to register.
They have some real fishing pros, and Hummingbird techs, that are on the board.
You will get more info there, for sure.
Let tham know type of waters you fish, and species you are targeting.
http://www.walleyecentral.com/forums/forumdisplay.php?f=34
I know there has been a lot of talk about these units and how to use them.