Most authors have little say over their covers.
We can only make suggestions, which are usually considered but rarely taken. Thus we throw ourselves into the hands of our publisher's art department, which knows more about cover art than we non-artist authors. That doesn't keep us from having opinions, however. And once in a while, an author doesn't like her art. I've been lucky at Avon, having had four of the prettiest covers of my entire career, but sometimes it's the luck of the draw.