Ovulation

I have a question.. So, you know how glow has your fertile week, it's green and has the percentages (which I'm assuming the highest is the day you're due to ovulate). And they say you get a positive opk 12-36 hours before you ovulate. So, when logging, I click "yes" to a positive opk and it's usually 2 days before the highest percent day. But then glow changes the fertile week and makes the positive opk day now the highest percent day too and shortens my fertile week. Why does it do that? Should I just say "no" when it asks for positive lh surge when logging?