Changing the labels on the login pop up

Hi,

I’d like to change the wording on the login pop up on my site. At the minute the pop up asks for username and password, all i’d like to do is change the value/placeholder text that appears in the username box so that is says ‘username or email address’.

I copied the form-user-login.php to my kleo-child theme an dplaced it in a bbpress folder but it doesnt seem to have changed anything. Is this the right file to edit? or is there another file i need to change?

Thanks,

Phil