Change URL for Cookie Free Domain

Hi, 

I have set up my wordpress site to serve static content from static.my-site.com to the live site www.my-site.com. In Wp-config I have defined, the cookie domain, content URL and plugin URL. 

H5P is recognising the new plugin URL however it seems to serve many things including js script URLs from the standard wordpress site_url, which now means the scripts dont load. Is there anyway of defining the site_url seperately either through pasting code into my theme functions.php or a plugin?

As you can see from the attached image, it is still trying to load scripts from the main domain. Any help would be apprechiated.

Thanks!

Ben