You don't need to put a cover on the dish—heating for 30 seconds at a time will keep the milk from overheating and splattering all over the interior of your microwave. It may be tempting to just put the dish in the microwave for 3-4 minutes at once, but doing this will cause the milk to heat unevenly and may even scorch or burn the milk. Don't let it exceed 212 °F (100 °C). If it does exceed 212 °F (100 °C), you will need to start over again with fresh milk. The proteins and chemistry of the milk changes when it boils and won't react the same way in your recipe as scalded milk would. Always use your hot pads to remove the bowl from the microwave. It may seem strange to heat milk only to let it cool down again before using it, but it's not the temperature of the milk that matters—it's what happens to the proteins during the scalding process. Let the milk cool to at least 105 °F (41 °C) before using it in your recipe. Putting hot milk into your recipe could ruin the other ingredients. For example, really hot milk could curdle or cook eggs, or it could kill off essential yeast.

TL;DR in Indonesian:
Panaskan susu selama 30 detik dengan panas sedang-tinggi. Berhentilah memakai microwave kalau susu sudah mencapai suhu 80 derajat Celsius. Biarkan susu mendingin ke suhu ruangan sebelum menggunakannya dalam resep.