Modify /sections/torrents/browse.php
Locate lines 182-190 and Comment them so that they match below:
// If grouping is disabled
/* if (($LoggedUser['DisableGrouping'] && !$_GET['enablegrouping']) || $_GET['disablegrouping']=='1') {
$DisableGrouping=1;
$QueryString.="&disablegrouping=1";
// If grouping is enabled
} elseif ($LoggedUser['DisableGrouping'] && $_GET['enablegrouping']) {
$QueryString.="&enablegrouping=1";
}
*/
Just below that add the following:
$DisableGrouping=1;