In the library, make your listing selections and click the Bulk Actions button.
The Bulk Actions button will appear towards the top right of your screen once at least one listing is selected.
Choose Edit Listings, then Package Details.
In the popup, select to Edit this page of listings only or Edit all listings at once and select Next.
If you selected to edit this page of listings only, in the popup, enter only those values that will change and be shared in all of the selected listings.
Once you've completed the changes, select Apply package details.
If you've chosen to Edit all listings at once, in the popup, enter only those values that will change and be shared in all of the listings, then select the Edit all xxx listings matching current search link.