If you want to edit the metadata settings on your photos you have in your list this is easy to do. You choose the photos you want to edit by select them (1). As soon as you select one photo, a black bottom bar is visible with some functions. When you have selected all the photos you want to edit you click on the button Manage selected photo (2).
When you have clicked on Manage selected photos you see the metadata settings the same way as you do when you upload photos. You can read how you manage the metadata here.
