Featured Image change

Dear Sirs,

Please, i′m trying to change the featured image for pages, in specific the home page.

I have used a filter of generatepress that is working at categories, author, search, etc, but at page i can′t make work..

This filter:

function change_featured_image_default_size() {

if (is_category() || is_author() || is_tag() || is_search()) {
    if (!wp_is_mobile()){
        return '750x400px';
    }
    if (wp_is_mobile()){
        return '370x200px';
    }
}
}
add_filter('generate_page_header_default_size', 'change_featured_image_default_size');

When i try to do it for home page:

if (is_page( '83717' )) {
	if (!wp_is_mobile()){
		return '750x400px';
	}
	if(wp_is_mobile()){
		return '370x200px';
	}
}

It doesn′t work… it presents the biggest image (full)

For the home page i′m using WP Show Posts…

Regards,

Tony