The first thing anyone trying to help you should ask is where do you live? You don't have to be exactly specific, just maybe what area of what state. I live in central Alabama. I have the same problem. Most coins I find are 0-4 inches deep. I have to find virgin spots that the old guys in the MD club here didn't cherry pick 25 years ago, that have coins near the surface.
I know that there are coins in the old areas that have been pounded, but they have sunken too deep for our mineralized soil to be seen even with an E-Trac.
Do what the other poster suggested and open up the right corner of your pattern. I would just open Quick Mask and hit the up arrow to eliminate FE 25 and higher, then hit the Detect button, and select yes to load the quick mask into the pattern.
The real innovation that the E-Trac offers isn't so much its depth, but its See Through, finding silver in junk.
Another thing, if learning the machine, maybe you should get some more practice finding clad in a clean park, learn what the coins sound like, clad are not that much different sounding and reading in VDI than silver. Read the manual, and Andy's book.