Make sure your instant pot (the inner pot, the lid and the ring) is completely clean. Rinse the inner pot with hot water and dry it. Place it back in the instant pot.
Pour the milk into the instant pot and adjust the lid. The valve can be either on sealing or venting.
Press the yogurt button on the instant pot and adjust it so the screen reads "boil".
Let the instant pot heat the milk. This will take about 60 to 90 minutes. Once it's ready, the instant pot will beep.
Take the lid off, and place the inner pot into an ice bath (a large bowl filled with ice water.
Place an instant read thermometer into the milk and read the temperature. It should show around 170 -180F.
Slowly stir the milk until the thermometer reads between 105 and 110F.
Take out ½ cup of the milk and mix it with ¼ cup yogurt.
Return the yogurt and milk mixture back to the milk in the pot and stir.
Place the inner pot into the instant pot again (dry the pot first).
Press the yogurt button again and adjust it to 8 hours.
Let the instant pot do its work and once the 8 hours is finished, your yogurt is ready.
Cool for an hour in the fridge and then store it in glass or plastic containers.