If the pattern you are running in is pretty much black, I'd say you have way too much discrimination. I'd suggest chosing either the Relic Program, or the Coin Program, and modify the audio and expert modes to suit your site.
I hunt for old coins at old sites. Farmfields, homesteads, old fairgrounds etc. In my neck of the woods, I typically run in Volume 30, Gain 30, response Normal, trash High, ground Neutral, Deep on, recovery Fast and Variabillity at 30. Sometimes I tweak one setting or another, depending on the circumstances. Knowing what settings will work best for you can only be determined by your understanding of what each setting does. As such, your choices may be different for your style and the sites you hunt than mine or anyone elses. Having used the Explorer successfully, you should have a good idea as to what many of the adjustments accomplish.
Personally......If I am hunting an area with an abundance of iron pieces (nails around old homesites), I prefer to run in 2-tone ferrous with a fairly wide open screen. (that means very little "black" on the screen) In cluttered areas, I always use a smaller than stock coil to maximize target separation. I run Auto Sensitivity at a +2 or +3, if it doesn't cause too much falsing. If I can see bits of iron all over the ground or if it falses with each sweep, I'll back the Sensitivity off as far as -1 or -2. I seldom (never) use manual Sensitivity in areas with lots of adjacent targets. I'm convinced that running with a higher Sensitivity than the software "recommends" will actually reflect the signal prematurely. If the falsing is caused by iron with consistent 01/35 readings, I'll reject (black out) a portion of the ferrous line. On the other hand, if I am hunting an area with "modern" trash (aluminum scrap, bottle caps etc) I prefer to run in multiple tone conductive mode. If deeply buried iron isn't a problem, I can "hunt by ear" with good results. I guess my point is, the more information I can gather from the audio, the less I have to look at the meter.
I'd suggest you reset the E-TRAC to factory default levels, and start all over again with your preference of settings. Again, if your screen pattern is pretty much black, you have way too much discrimination going on (in my opinion). HH Randy