If you're prompted with the Confirm Unsubscribe Link pop up every time you try to save your campaign, the problem will be with the Template.
This error appears when you haven't locked down the area where your unsubscribe link is.
To fix this, navigate to the Template and click the Drop Down Menu then Edit.
Click the Settings cog above the block where your Unsubscribe link is and tick the User Editable box.
This option will lock down the content block and stop the Confirm Unsubscribe Link from appearing when saving campaigns.