How do I update this app?

I had a little scare today with constant spotting. I was able to get in and see a doctor today. I found out my body is getting rid of old blood left in my body. Otherwise, I had my first ultra sounds and the baby is fine! Cute little heart flickers! Even better I’m 6 weeks a long rather than 5 weeks. My app says 5 weeks and a couple days. Is there a way I can update the app and change it to 6 weeks. I’ve been trying to figure it out and I’ve had no luck....