After woocommerce updating search result not showing as price low to high.

The ordering of products depends on this field: https://cld.wthms.co/mYyLsu

It is set up and the default is configured at Appearance > Customize > WooCommerce > Product Catalog in WC 3.3+

But in woocommerce 3.2.6 its working perfectly i dont want to select that drop down by default it showing product search result as low to high. But in woocommerce 3.3.3 version default search result showing as random. Even i selected sort by price (asc) in Appearance > Customize > WooCommerce > Product Catalog section in woo 3.3.3 the search result page showing result sorted by random. please see attached screen shot https://www.screencast.com/t/bnbSnS6Joq1c

And also iam taking about the search result page not the shop

Ah right, so search results start with the “relevance” orderby by default. Since the user is searching for a specific term, this makes sense. You can see this happening here: https://github.com/woocommerce/woocommerce/blob/5bea7de93c152f15207750c3dd7e1a5ab6b6a0f8/includes/class-wc-query.php#L436-L438

You can change this behavior with some custom code using the woocommerce_get_catalog_ordering_args filter.

How i change the orderby “relevance” into price low to high on search page? If there any hook or function available for that?

woocommerce_get_catalog_ordering_args is the hook you can use to change this. It passed in args, and you will want to change these two if in a search query:

$args['orderby'] = 'relevance';
$args['order']   = 'DESC';