Rather than editing each contact separately, it will probably be easier to select a group of contacts and set their privacy settings using batch processing. First of all you will need to filter the contacts so you can select all before starting the batch update. Information on filtering the contacts can be found here.
To batch update the selected records click ‘batch update’ from the ‘Actions’ button. You can now select the changes you wish to apply to the selected records. In this example the selected records will be set to ‘Opt-in’ status and ‘Verified’. The source will be set to ‘Verbal’:
It is also possible to cleardown data from this feature too.