The right side of the screen is ferrous zone 0 then going towards the left side the next zone is 1 then 2, 3, 4,..........to 31. Conductivity starts at the bottom of the screen at 0 then 1, 2, 3.............31. The upper right corner would be 0/31 if the target has zero ferrous content and maximum conductive. A silver coin will hit at 0/31 and also at 0/31 or even 1/29 but other coins should not hit in that area. A penny hits in the 3/28 are as copper and silver are the best conductors. A penny and silver may be close but there should be a difference. A good test would be to see where a nickle hits as this should be down around 11/5. It looks as if the calibration is off or the coil has a problem. A smashed aluminum can will hit in the upper righ corner but has a much larger sound in pinpoint than a coin.
Try the nickle test and see what happens. It is working properly for a silver coin and a smashed can and a penny will be close to the upper right so another check is needed. A penny should not read 0/31 or 0/30 or even 1/29, anything in that area.