This is good advice, but it's also sort of like taking painkillers when you have a broken leg: it helps with the symptoms but doesn't address the underlying problem. If you have mold growing on top of the soil, it almost always is because the plant is being over-watered. Make sure the pot the plant is in has good drainage (a nice big drain hole at the bottom) and that the top layers of the soil have a chance to dry out between waterings.