Have you flushed the cache by visiting the page with a ?flush=1? yoursite.com/?flush=1. You can also try empty your browser cache (ctrl + f5 on firefox). Also if its not changing after using ?flush=1 then make sure you are editing the right file.
By appending ?flush=1 to a SilverStripe URL, you only delete the cache of that page, not the whole cache. So if newssection is the page where you altered the .ss file, the behavior is normal.
To flush the whole cache, run /dev/build?flush=all