Bring milk to boil in a medium size non-stick pot on high heat (option to do this in the Instant Pot by using the Saute function on high temperature).
Cool to near room temperature.
Add yogurt and sugar. Stir to mix. Divide the mixture into 4 heat proof cups. (If you used the Instant Pot for these steps, clean out the Instant Pot, it will be used in the following steps.)
In the Instant Pot , add 5 cups water. Place the 4 heat proof cups into the inner pot. Close the lid and choose “Keep Warm” function for 15 minutes.
Let the pot stand for 10 hours closed.
Open the lid and take out yogurt. Cover with plastic wrap and chill a few hours before serving.