Nowadays whenever I make soy yogurt, I do it in the Instant Pot pressure cooker. It's super easy. You take a glass bowl, fill it with soy milk, as little or much as you want, add yogurt starter, whisk to mix well, put the bowl in the Instant Pot. Put on the lid and turn on the yogurt setting. I up the time to 12 hours. How long depends on your tastes and your yogurt starter. I use this for yogurt starter. Only 1/8 tsp is needed for 1 quart of soy milk. I use Edensoy unsweetened for the soy milk. Westsoy also works well, it's just not as thick as Edensoy. The soy milk should be room temperature--no need to boil it first like you have to do with cow's milk (to sterilize it). There are other brands of yogurt starter you can use, or you can use store-bought yogurt for starter. Whatever you choose will affect the flavor of the yogurt, so experiment for yourself to see what you like best. Some are more sour than others. I tend to like a less sour taste.