Edit Jetpack subscription.php

I’m trying to change the widget heading for the subscriptions widget to lower case. I went into …/plugins/modules/subscriptions.php and found “Subscribe to Blog via Email” under ‘public static function defaults()’.

I changed it to lower case and saved, but it’s still showing up on my site (www.lynnunderwood.com) with upper case letters. Clearing my cache and the rest of recent history for today doesn’t seem to help.

What am I missing?