For sort by "Name A-Z" (ascending)
Got to this path
catalog/controller/product/product.php
change code
Original Code
if (isset($this->request->get['sort'])) {
$sort = $this->request->get['sort'];
} else {
$sort = 'p.sort_order';
}
Change Only else part
if (isset($this->request->get['sort'])) {
$sort = $this->request->get['sort'];
} else {
$sort = 'pd.name';
}
For disable the "Search in product descriptions with 2 way.
Solution 1
remove or hide descriptions checkbox, check image below

Solution 2
Got to this path
catalog/controller/product/search.php
Original Code
$filter_data = array(
'filter_name' => $search,
'filter_tag' => $tag,
'filter_description' => $description,
'filter_category_id' => $category_id,
'filter_sub_category' => $sub_category,
'sort' => $sort,
'order' => $order,
'start' => ($page - 1) * $limit,
'limit' => $limit
);
Change only one line remove it or comment it.
$filter_data = array(
'filter_name' => $search,
'filter_tag' => $tag,
/*'filter_description' => $description,*/
'filter_category_id' => $category_id,
'filter_sub_category' => $sub_category,
'sort' => $sort,
'order' => $order,
'start' => ($page - 1) * $limit,
'limit' => $limit
);
