xoducky hi charlie, my apologies for the late response!
we don't have subaccounts enabled for the obvious reason - that each member is only supposed to have one account - and so i don't believe that we can switch the author. i'm wondering if it would be better for you if that ad was just archived so that you could post a fresh one from your account? you can request that it be archived here, and as soon as an ad mod has handled that you can repost.
if that's not a solution you'd like, then tag me in a reply here and i'll be happy to swap out the image links for you!