Register for this site – title change

Hi there,

On the register page, there is a little subtitle on it with the words “Register for this site”.
Where do I change the wording for this?
I’ve looked in all the CSS and PHP files in the plugin but I can’t find it anywhere. I’ve spent the past two hours looking for it. I’ve even tried to find it on the page source in Safari (I found it in there, but still couldn’t trace it back to where it would be in the CSS and PHP). I give up.
Please throw me a bone.
Thanks
Cora