how to make post titles on multi post pages - h1 and not h2

Hi

hope someone can chip in here.....

in the ATO it says that if you choose the single page posts title to be H1 - the post titles on all multi post pages will still be H2.....

what code and what file do i need to change in order for the post titles on all multi post pages to be H1...., without changing the fact that all the post titles on the single page posts are configured to be H1.....

thanks!!

miki