Frustration

Halo

ok so Glow just moved my Af day up by 2 days. I went from Af being due 10/11 to now 10/9, and it's showing I'm only going to have a 1day flow. I'm beginning to distrust this app more and more, but I'm also having a hard time letting it go. someone please help me understand what the heck is going on. My cycle day changed, but the day of ovulation remained the same, but that doesn't make sense. If my predicted af changed why didn't the ovulation day change. I'm just trying to get and understanding on the math and concept.