Q&A allowing visitors to ask questions, how do I stop that?

Hello there!

I want to use Q&A for a community website. Lets say:
http://soyciencias.org/questions

My Q&A is configured in a way that outputs:

[Q&A] After Visitor Submits a Question setting requires registration of the visitor, but your website is closed to registrations. You may consider to fix this using plugin settings or Wordpress settings.

What I want is only logge din users being able to ask questions, so I thinkg Q&A is on it's right configuration. Wordpress registration is disabled because the website is not yet ready.

But something is wrong:
1. As a visitor, go http://soyciencias.org/questions/ask
2. Fill the form
3. Press "Login and submit"
4. Do not login (because you don't have an account)
5. Your question is already published in http://soyciencias.org/questions

What I whant:
5. Your question is automagically rejected, since you are not a logged in user

What config should I touch?
Thank you!