Display posts by alphabetical order

You can change the sort order on a category archive page to show posts by title (A-Z) by adding this code to your child theme’s functions.php:

/* Sort posts by title for a specific category */
function change_category_order( $query ) {
    //Sort all posts from category with id=3 by title
    if($query->is_category('3') && $query->is_main_query()){
        $query->query_vars['orderby'] = 'name';
        $query->query_vars['order'] = 'DESC';
    } 
}
add_action( 'pre_get_posts', 'change_category_order' );

You need to replace “3” with the correct category id. You can find out the category id by heading to dashboard => post => categories and hover over the category you want to adjust the sort order.