Proper set up for lowrance sonar

Question

what is the best way to set up sonar for best results. there are so many different settings, its kind of confusing. also my unit looses contact with the depth reading and starts flashing weird numbers, it does it more than what it actually works correctly.
also is there some kind of video that you can watch, that actually shows a professional setting up and explaining how to set up a unit. i have a lowrance x135