There are instances when adding impacts, where you would want your club or group to be auto-selected for sharing purposes. e.g., if you made an impact to a club, and you were reluctant to share it with the University, even with the setting on, you may deselect it from sharing.
Note: This auto-share setting is only to help default the selection for data to be shared.
To default this setting, you may login and navigate to your Dashboard -> Groups. For each group you are a member of, there is a link enabling you to auto-share your impacts.