How To Bulk Edit Contacts
To bulk edit your contacts, go to the contacts screen and make a search for the contacts you want to edit.
Next to the bulk actions screen, there is a More Actions dropdown which you can click to reveal more actions.
Select Edit Contacts to go to the contact editing screen.
On the edit screen, you will be able to make changes to any field, including custom fields setup with the Custom Fields Management plugin.
Scroll to the bottom and click Edit Contacts to being the update process.