Can I change the header of public pages to HTML5?

I’m trying to modify the header in the generated pages. I can go Config, then Settings, then “subscription-ui settings”, then “Header of public pages” and drop in my own HTML5 header, but it doesn’t replace the default XHTML, it just appears below it in the generated pages. See:

http://librarianendorsed.com/loveletters/?p=subscribe (and View Source)

This has come up once before, but the person who asked the question also answered it, though not in a way that I understand.

Hi, I think you need to make a feature request - if you go to phpList.org and go to the developers home page you can see the “i would like to report a bug” - the process is the same for feature requests.