In Genesis Page specific layouts override the default layout from theme settings. But the same does not apply for the Page set as Posts page (in Settings > Reading). Regardless of what layout you select when editing this Page, the default layout will continue to be used unless the following code is added in the child theme’s functions.php:
/**
* Make Posts page obey its Page layout setting
*/
add_filter( 'genesis_pre_get_option_site_layout', 'sk_do_posts_page_layout' );
function sk_do_posts_page_layout( $opt ) {
if ( ! is_home() ) {
return;
}
$opt = get_post_meta( get_option( 'page_for_posts' ), '_genesis_layout', true );
return $opt;
}