I agree there are piles of older coins pretty close to the surface in many areas,it has a lot to do with where you are searching. I try and hunt the oldest possible areas and am finally starting to dig older coins fairly consistantly. Old abandoned or demolished homes will always yield coins,especially near the driveways,under the clothesline and anywhere that kids played alot. Im sure your detector is picking up coins deeper than you are finding them. When coins are a little bit deeper the sound of them is a lot fainter,may just barely beep on your detector,what you want is a sound you can repeat consistantly even if only in one direction and of course the target should be deep enough to justify the deteriorated sounds. I used to only dig clear repeatable sounds so I was usually digging the louder sounds and found almost exclusively newer coins,now I lower my tone standards dependant upon depth the target is reading. If you plan to keep using that machine seriously you should read everything you can find in forums on the net,this has helped me tremendously since ive never had anyone help me in person and have only detected with others on a couple of occasions. Think of yourself as trapped on an island and the MD is the only weapon you have and coins and relics are the only things available to hunt.
Above all else the spots you choose to hunt are the real determining factors with regard to the items you will find,if people werent there dropping stuff years ago the items will never be there. If you find yourself getting frustrated at the older sites go hunt some clad at playgrounds,ballfields,fairgrounds,outdoor ampitheaters,ect... Finding some good easy targets will put you back into the right frame of mind,its been a pretty good crutch for me during the learning process. Then come home and checkout the todays finds this will fire you up to go back to the old places,over time you will find yourself spending more and more time at the older places as well as making more finds. Stay with it and dont give up and try and give some of the little bitty sounds a dig now and then...Shoot