EDITED to update that I figured it out, and since I don’t seem to have the power to delete my own topic, I thought I’d post the answer here for other new editors like me:
I got the news that I dread, an author contacting me to say that her name is spelled wrong in her published article, in the PDF and not merely in metadata. If you need to change a published PDF, go to Submissions, go to Archives, click on the article title, and on the page for that submission, scroll down to Galleys. Click the blue arrow next to PDF, and you will see three options: Edit, Change File, Delete. Click on Change File to upload the new version of the article. Click through just as you did in publication to save. The new version is now available with no effect on the download counter or DOI.
Feels silly to type it all out but I could not find this info anywhere online. Hope it helps someone who comes looking!