Sort Employees name by first name

Hi, I have SuiteCRM 7.5.1 running on Apache 2.2.

I wanted the Employees module to sort the employees by first name instead of the last name.

So I changed these lines in ListView.php:

if (($this->sortby == 'name' || $this->sortby == 'last_name') &&
			str_replace(' ', '', trim($subpanel_def->_instance_properties['sort_by'])) == 'last_name,first_name') {
			//$this->sortby = 'last_name '.$this->sort_order.', first_name ';
			$this->sortby = 'first_name '.$this->sort_order.', last_name ';
		}

and these lines in ListViewData.php:

if (!empty($params['overrideLastNameOrder']) && $order['orderBy'] == 'last_name') {
			//$orderBy = 'last_name '.$order['sortOrder'].', first_name '.$order['sortOrder'];
			$orderBy = 'first_name '.$order['sortOrder'].', last_name '.$order['sortOrder'];
		}

cleared the application cache, the browser cache and restarded Apache, But the employees module still sort the employees by last nameā€¦

These tweaks worked on version 7.1.4, they are not working on version 7.5.1

Any help would be appreciated.

Thank you.