If you built your family tree on your family site online, please read the following article: How do I edit the date of a photo on my family site?
1. Open your family tree in Family Tree Builder.
2. Click on the ‘Photos’ button.
3. Double-click on the photo to open the 'Edit Photo' window.
4. Edit the date using the small calendar icon and click ‘OK’.
5. Save your tree and sync it with your family site.