The beauty of the F75 is the almost infinite settings for your type of hunting that you do. No, the F75 has never been known to be a quiet detector! That is because it is so sensitive. Now, having said that, I would guess that you are setting the sensitivity on your F75 as high as you can. If that is the case, then that is part of your problem can is causing the F75 to run 'hot'. You do not need to set the sensitivity at max to get good depth. Start with sensitivity at 60 and start to get a feel for the ground and conditions and then adjust sensitivity up or down to suit the situation. Turn the sensitivity down if you are getting falsing. Only run it as high as needed without the falsing.
Also do an auto ground balance or a manual ground balance and then manually add three numbers to the ground balance. If the F75 auto ground balances to 60, adjust to 63 try this and see if it helps. It works for me in my mild ground. Run in the FA mode as it is super fast and you will hear the good signals clearly among the trash as the separation is so good in this mode. I hunt in extremely trashy parks and they are fairly new so the clad is not real deep and this is how I set up my F75 and I get lots of clad and many times the trash is in the hole with the clad and the F75 picks it out. Try the 2l tones. When you get a good hit, then notice the numbers on the display. That works real well for me. You might like that.
Each of us hunt in our own ways for where we hunt, how we hunt and what we are hunting for and how it suits us and our ability to be able to hunt. I an 67 and can not stay out near as long as I would like or once did. I hunt new parks where there are no relics and no silver or anything old so my hunting is for clad with some jewelry surprises every so often. I have developed my way of hunting with the F75 that suites my style. I hunt with 0 disc and then notch out everything except the nickel notch and hunt the clad. Yes, I am well aware that I could miss some gold but I accept that and more than make up for the gold by the numbers of good targets I dig in my trashy parks. With the settings I mentioned above, I still get some noise but the good targets come in just great and I get my fair share of goodies and little trash on each hunt, and I go 3 or 4 times a week. I also get lots of nickels that others have passed on. As time goes on, you will develop settings that suit you and your way of detecting. Dig it all if you want or set disc and notch for your type of hunting. It is up to you. Just hang in there with the F75! It is a wonderful detector!!!