shell thickness or perimeters = 3 is normally sufficient. I run mine at that most of the time. For clear filament, you may need 5 to block out infill. I just let it show thru or use a color. I only go higher if I need the physical strength, or lower if I need a thin wall. The same goes for top and bottom layers. 2 for the top is totally bad for covering over infill with any color.
Infill settings should be based on the functionality of the print. I have done maybe 1 @ 100% and a couple @ 50% and have found that 20% is about the highest I ever need to go 97% of the time.
You may be having other issues and think it is infill. A quick test would be to print with 0% infill and see if it still shows thru.