From this post, I know the default is:
"Students cannot view previously submitted comments by any other reviewers, including comments by TAs or other instructors."
I want students to ask unique peer review questions for each assignment, but this is not currently possible using these settings as they can't see what their peers write. Is this just something that is impossible by design, or is there some setting I can change?
I saw on another post that an alternative would be to have students conduct peer reviews in Discussions, where each comment would be visible to other users, but I was hoping to find some functionality using the Peer Review system.
In my experience the quote you have copied should say "student reviewers..." The student who submitted the original assignment will be able to read all comments.
Student reviewers can pose questions for the original student to respond to. You will be able to see the question and answer, but the reviewers will not be aware of the answer. to their questions.
If you use a rubric, you will unfortunately need to choose between allowing students to continue seeing how their peer reviewer "graded" the rubric, and using the rubric yourself to assign grades. I usually grade rough drafts with very simple requirements that I describe in the instructions, and let the peer reviewers use the more detailed rubrics that will apply to the final paper. I enter only a score, after the peer reviews are complete, and the filled out rubric (with a different score by a reviewer) remains visible to students.