After you launch a campaign, there are times you may want to make a change. Any time you make a change to the emails or steps in a sequence you should relaunch your campaign to apply the edits. Changes are NOT applied to your campaign until this is done.
After you have made the changes, click on the "Apply Edits" button:
This will take you to a page where you are able to review the changes before they are applied. On the bottom right you will need to select "Go Live":