Change the words “Tell us your name”

My clients need confidentiality as well as give reviews with a name on them.
Not impossible.
I just need to change the words from “Tell us your name”
to “Tell us your second name only (will be published)”

also

How can I change a name once the client has submitted?
I want to hide their surname and keep their names if they disclose too much information.
This is a way I can solve the problem too.

The page I need help with: [log in to see the link]