wordpress seo yoast change xml sitemap priority for taxonomy

I’m using wordpress seo yoast plugin in to a web site.In the xml sitemap settings I enabled yoast plugin sitemap and it is working fine.In the admin panel there is the taxonomy named “stores”. This is like categories. But i need to set it’s priority from 20% to 60% in the store-sitemap.xml file.

I added following filter and it is not worked and not displaying to set the priority when adding or editing the stores.

add_filter( 'wpseo_metabox_prio', 'move_yoast_metabox_down' );

function move_yoast_metabox_down( $priority ) {
    return 'high';
}

But this priority setting option can be view in the post types.

If anyone has solutions appreciate it.
Thank you