Setting youtube size in functions.php

I'm using the code below to set the width and height of youtube embeded links

//////////////////////////////////////////////////////////////////
// Youtube shortcode
//////////////////////////////////////////////////////////////////
add_shortcode('youtube', 'shortcode_youtube');
function shortcode_youtube($atts) {
    $atts = shortcode_atts(
        array(
            'id' = '',
            'width' = 845,
            'height' = 500
        ), $atts);

        return 'div class="video-shortcode"iframe title="YouTube video player" width="' . $atts['width'] . '" height="' . $atts['height'] . '" src="http://www.youtube.com/embed/' . $atts['id'] . '" frameborder="0" allowfullscreen/iframe/div';
    }

For example, I will place this link --> https://youtu.be/YQHsXMglC9A , in the post and it automatically embeds.

The code above isn't rendering the width and height. I also tried the code below.

add_filter( 'embed_defaults', 'change_embed_size' );

function change_embed_size() {
// Adjust values
return array('width' = 800, 'height' = 500);
}

That didn't work either. Also that code seems like it targets all embeds on the site I want it to specifically target youtube.

Is there another option or way to make any of these work.