Appleâ€™s Photos app is remarkably good at identifying people in your snapshots and collecting all the pictures that contain a particular person into a group in its People view. At its top level, the People view shows a thumbnail photo for each person, picking one automatically from all the available photos. Needless to say, it doesnâ€™t always pick the photo you want, so if you dislike whatâ€™s there, you can change it easily on the Mac. In Photos, click People in the sidebar and double-click the thumbnail of the person you want to change. If necessary, click Show More to see all their photos, then Control-click the desired photo and choose Make Key Photo from the contextual menu.