Glow Changed Ovulation Day

Hi everyone, it's my first month off BC so this month was bound to be a bit strange! I definitely ovulate on 10th Aug (OPKs were positive and weren't before, and I felt rotten!), so AF wasn't due until this Friday. However AF showed up last night. I logged this in glow and it changed ovulation date to 5th Aug even though I logged negative ovulation tests for that date. How can I manual change the ovulation date so I can keep a more accurate record? Esp if this keeps happening each month.

Thanks xxx