Olha, creio que seja isso:
Themes/default/index.template.php
// Show the total time logged in?
// Show the total time logged in?
if (!empty($context['user']['total_time_logged_in']))
// Show the total time logged in?
// Show the total time logged in?
if (!empty($context['user']['total_time_logged_in']))
{
echo '
<li>', $txt['totalTimeLogged1'];
// If days is just zero, don't bother to show it.
// If days is just zero, don't bother to show it.
if ($context['user']['total_time_logged_in']['days'] > 0)
echo $context['user']['total_time_logged_in']['days'] . $txt['totalTimeLogged2'];
// Same with hours - only show it if it's above zero.
// Same with hours - only show it if it's above zero.
if ($context['user']['total_time_logged_in']['hours'] > 0)
echo $context['user']['total_time_logged_in']['hours'] . $txt['totalTimeLogged3'];
PS: Tire backup antes, porque não testei!