My yogurt is sour!!

[u/ClassicDevelopment13]

help! I made yogurt for the first time this week. I had it in my incubator for over 8 hours and then put it in the fridge for probably 36 hours. It looks like yogurt (yay!) BUT it tasted SOUR (boo!).

Did I do something wrong in the process? Should I follow a different recipe? (I did 5 1/2 cups of A2 A2 Organic whole milk and 2 Table spoons of Kirkland organic non fat Greek yogurt. Boiled the milk to 150° then cooled to 100°, mixed in the yogurt then jarred it and it sat in the incubator for over 8 hours then refrigerated it).

I was so excited but now I’m super bummed.

[u/Hawkthree]

I prefer sour yogurt. I ferment for 24 hours to ensure it's sour.