How to change comment prompt?

Do you have any experience editing php files? What theme are you utilizing? Often times that text will be included in the comments.php file of your theme.

This is a link to the comment_form section in Codex which shows a few different ways to utilize comment_form within that file: https://codex.www.ads-software.com/Function_Reference/comment_form

Hi,

What if later the theme is upgraded? In that case, the modification may be overwritten by the new upgraded versions?

Yes, this is true. Anything you change would disappear upon an update to the theme. You would want to utilize a ‘child theme’ to avoid that (https://codex.www.ads-software.com/Child_Themes)