In Magento, I am change the product visibility of configurable child product but not work Properly

Here is my block code

$filteredProducts = $productCollection->addAttributeToSelect('*')
    ->addAttributeToFilter('entity_id', $parentID)
    ->addAttributeToFilter('type_id', array('eq' => "configurable"));

    foreach($filteredProducts as $_product) {
        $_children = $_product->getTypeInstance()->getUsedProducts($_product);
        foreach ($_children as $child){
            if ($child->getID()) {
                $array =  [ 
                    1 => 'Not Visible Individually',
                    2 => 'Catalog',
                    3 => 'Search',
                    4 => 'Catalog, Search'
                ];

                $currentValue = array_search("Search",$array);
                $child->setVisibility($currentValue);
                $child->save();
            }
            echo "<pre>";
            var_dump($child->debug());
        }
    }

This works only frontend and not apply in product grids.