Batch change metadata
You can select a group of photos and make metadata changes to all the photos at once. For example, if you need to add the same set of keywords to a selection of photos, or change the version name format, you can select the photos and use the Batch Change dialog to change them.
Change the metadata associated with a selection of photos
Do one of the following:
Choose Metadata > Batch Change (or press Shift-Command-B).
In the Info inspector or the Info pane of the Inspector HUD, choose Batch Change from the Metadata Action pop-up menu .
In the Batch Change dialog, choose the metadata preset you want from the Add Metadata From pop-up menu.
Click Append to add the preset’s metadata to the photos, maintaining any currently associated metadata, or click Replace to add the preset’s metadata to the photos and remove any other associated metadata.
Enter any additional metadata you want applied in the metadata fields.
Specify any other metadata options you want to change, then click OK.