BvK

Hi, Full disclosure, I have fished for over 50 years but only just getting into bass fishing and electronics. I bought my first sonar, a Lowrance Hook2 4x. I am having issues with it that I cannot seem to find a solution to. If you look at the picture (I have resolved the interference you see with a second battery). 1. The main issue is the depth range shows 40 to 60 feet, rather than showing the whole water column. This is very frustrating I cannot seem to find settings to change it anywhere. If I change it to a different depth, it often shows no bottom, but nothing I do seems to be able to get it to show the whole water column. The transducer offset is set to 0, I have checked many times. 2. The double bottom, I believe I have to reduce the sensitivity for this, am I correct ?. Thanks folks !