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;