WP super cache expire headers

Hi

So on GTMetrix I get this call “Add expire headers”. Now I have used WP super cache and it seems to take care of a lot of caching and stuff. But I guess it does not do anything for expiry headers?

So I added some code in the file editor backstage to make the exiry headers work. But I sitll get that messge on GTMetrix “add expires headers”. But maybe that is because it takes some time before it goes through and GTMetrix don’t sense this change right away?

Or do WP super cache interfere with the code I have added to enable expires headers in some way?

thanks