charts

Is there a way to go in and manually change my charts. I have charted on paper for 12 years as a form of prevention and for conception. I jknow that I ovulate between day 12-16 and my luteal phase is 12 days.  So far, this app has messed up three months now and is putting my ovulation at day 8 or 9.  I would love this app if it were accurate because the recording is so simple!