Open the post in the editor
To open the post in the editor, press the 3 dots beside in the post header (or if you are on the post page, press the 3 dots in the top right corner) then select the "Edit" option.
Make any content edits you want
Update your post with the changes you had in mind. Once that's done...
Press "Update Post" in the top right corner.
This opens the publish modal. Here you can choose where you want to republish this post.
Press "Update" or "Republish" beside each platform you want to publish to. Or "Unpublish" if you want to unpublish from all destinations.
Press "Schedule" or "Publish" to republish this post for later or right now.
Your post will be republished to the selected platforms with your edits made! Just note that for 3rd party platforms, you may need to delete the original post (if you haven't already).