In order to change this you have to override the logo() function in your themes qa-theme.php. If its not present, create that function andd add your changes in there. The original logo() function looks like this:
function logo() {
$this->output(
'<div class="qa-logo">',
$this->content['logo'],
'</div>'
);
}
Where $this->content['logo'] is the link and the logo image or Website name printed as an <a> tag.