Has the referral system always been this unclear?

So I send someone to http://www.paperbackswap.com/index.php?r_by=juanito

After they complete the initial signup form on the main page, and enter their full name, email and a password, they are sent to the next page. 

Where they check a box and agree to the terms. Then they are sent to the next page (third one)..

On this next page, one of the optional questions is "Did an existing member refer you to our website?   Yes   No"

If the user selects Yes, then my nickname appears. Why isn't this already set to yes? It should be. People should have the option of changing it to no, but it is clear that they ended up on PBS because of my referral link.

If the user doesn't select Yes, and just leaves it on No, is their signup considered to be under my account (regardless of whether they add books or not, and I get a credit)?

Frankly I find this disappointing. I was planning on putting something up to mention this site to neighbors in my apartment building, but unless I'm very clear about how they need to select yes on that form field, then I'd likely not get a credit. And while, it's all about the free books (which I agree with), it feels a little deceptive to me. I'd also like to know the people who I refer so I can contact them if I choose to.

I do want to make this clear that I'm writing this message as a huge, huge fan of PBS, not someone who is just looking to complain and cause problems. Thanks!