Thank you for posting this question. Currently there is no way to configure this. As you have already noticed, the logs overwrite themselves after 10 days. The only workaround for this is to make a manual backup every 9 - 10 days.
Vlad Ivascu Technical Support Engineer Okta Global Customer Care
Thank you. In case this comes up in anyone else's search I'd like to clarify that in our environment, AD agent logs roll to 10 interations in about 6 hours, so we get less than a day on the logs. It appears it isnt measured by days, but by number of logs in the directory.