How to change to search label for the store locator
As of Yoast SEO 20.0, the settings interface inside our plugins has received a major overhaul. Please update to the latest version of Yoast SEO if your plugin does not look like the screenshots you encounter in our Help center.

The store locator’s first field, by default, is labelled with: Enter your postal code, city and / or state
As of version 7.5 of Yoast SEO: Local, this label can be customized using the developer filter: yoast-local-seo-search-label
.
add_filter( 'yoast-local-seo-search-label', function( $search_label ) {
$search_label = 'Your new search label';
return $search_label;
} );