Final answer:
When replacing drywall fasteners, the heads of the screws should be covered with joint compound.
Step-by-step explanation:
When drywall fasteners are replaced, the heads of the screws should be covered with joint compound. Joint compound is a material used to cover the screws and create a smooth surface for painting or finishing the drywall.
It helps to blend the screws with the surrounding wall and provide a professional finish.