Editing "leave a comment" link text

Hi,

First of all, I have created a child theme for the theme FlatOn. I need help in finding which file I have to edit to change the “leave a comment” text to something else.

Also, before I created the child theme, I located the “leave a comment” text in template-tags.php and edited it to “Please leave a comment” and it worked but I can’t seem to get this same change to work now that I am using a child theme of FlatOn. Do I have to copy the entire contents of the template-tags.php in the parent theme and create a file with same name in the child theme and paste the entire contents there?

Any help much appreciated. Thanks!