I have a php function script that is supposed to uncheck a checkbox or checkboxes if a user unchecks it when the preview button is clicked but I can only get the last checkbox that was unchecked to stay unchecked but not the other checkeboxes how can I fix this so that all the checkboxes that where unchecked stay unchecked?

İşte bana sorun veriyor benim PHP fonksiyon parçasıdır.

if(isset($_POST['preview'])){
    foreach($query_cat_id as $qci) {
        if(!in_array($qci, $cat_id)){
            $unchecked = $purifier->purify(strip_tags($qci));
        }
    }
}


for ($x = 0; $x < count($query_cat_id); $x++){
    if(($query_cat_id[$x] == $cat['id']) && ($cat['id'] != $delete_id) && ($cat['id'] != $unchecked)){
        echo 'checked="checked"';
    }
}