image_default_size doesn't change in wordpress
<p>I'd like to change the default size for images within posts. I've tried to edit both the <code>/wp-admin/options.php</code> page and the <code>functions.php</code> file, but none affect the size. They do work for the default alignment and the default link, but not for the size.</p>

<p>Here's the snippet from my functions.php file</p>

<pre><code>    add_action( 'after_setup_theme', 'default_attachment_display_settings' );

function default_attachment_display_settings() {
 update_option( 'image_default_align', 'right' );
 update_option( 'image_default_size', 'large' );
}
</code></pre>

<p>The images keep showing up as "full size".</p>