Different question – same answer: How could I reset the “Already Posted” status? . I cloned the post, but I am getting “-=Duplicate=- Post ID: XXXXX Already posted.”
Format settings are saved individually with each post. Any changes you make in the general settings page will affect only future postings. if you have drafts and/or scheduled posts they will be posted with old settings unless you change them manually for each post.
If you changed the format for already published post, please don’t forget to save the post before clicking “Repost” button.
UPD: Version 3 has a special button that you can use to reset all existing settings to the current default values.