Once you select the green thumbs up on the Approve Reviews tab, both scores and comments are already published on your website.  
The Preview tabs allow you to quickly, at a glance, review to check for any errors without having to open up your company's website.  Should you find that you made an error (ie: forgot to change the reviewer's name or add their city), simply make the change in Approve Reviews.

To change/update a review via Approve Reviews:

1.  Deny review by changing from green thumbs up to clear.

2.  Make change.

3.  Approve by changing the clear thumbs up to green.