Hi, I may be able to help. I am very new, unfamiliar with template/website coding extra, but I was able to change the standard ' Leave a Reply' to 'Leave a Comment'. If you are looking to change the text, here's some extplanation of how to do it:
First, go to Dashboard.
Go to ---> Appearance.
Go to ---> Editor.
Go to ---> Comments (comments.php).
DO NOT click on any text, but in an EMPTY part of the screen hit CTRL + F. This brings up a "Find" box, making it easier to find code. Copy and paste or type in the find box: Leave a reply. This makes it easier to jump and find the section you're looking for. The screen will jump you to the phrase or section of code you're looking for. Ultimately, you'll locate this code to modify:
<a name="commentform"></a><!-- named anchor for skip links -->
<h3 class="reply"><?php comment_form_title($noreplytext = __('Leave a Reply','atahualpa'),
$replytext = __('Leave a Reply to %s','atahualpa'), $linktoparent = TRUE); ?></h3>
Simply change 'Leave a Reply' to you're preferred phrase, such as 'Leave a Comment'.
Once you've edited the text, don't forget to save. This worked for me. I hope that helps.