Hi Lisa,
Everything looks OK as far as I can see. I have logged in as Amy and looked at the two forums and your identity is displaying correctly.
In the first example I could believe it to be human error as Natalie does reply within the same set of nested responses.
In the second, Natalie does reply to the thread but much further down than Amy's comment.
If it happens again can you ask what the other student has seen? If you can confirm that others are seeing your details displayed incorrectly rather than just referencing incorrectly then we can look into it further.
Wesley