Search and filter for the group of contacts you want to change or tag.
Select those candidates
Choose Bulk Change under the 3 dots
Make the changes to the Global Status, Owners, Source, Type, etc.. The changes you enter will replace the data previously in those fields.
To edit Tags - choose Add to add a current tag to an existing contact record choose Replace to replace all tags with new tags (all previous tags will be removed). Click Set Tags.
6. Save your changes by selecting Bulk Change at the bottom of modal
Check out Dan's video here.