How I can set a different slug for store post type?

You can achieve your goal simply adding following code in the file functions.php of your theme.

add_filter( 'yith_sl_rewrite_slug_post_type', 'yith_sl_rewrite_slug_post_type' );

if( !function_exists( 'yith_sl_rewrite_slug_post_type' ) ){
    function yith_sl_rewrite_slug_post_type( $slug ){
        $slug = 'point-of-sale';
        return $slug;
    }
}