Apple Preview: While moving/editing text boxes created by others in a PDF, font color of that text changes for some reason and I don't want it to!!

I have a project where I've given about 10 people 50 PDF files each to mark up in red text, and send back to me. When they send them back, I in turn need to move or edit some of the text boxes they have created in Apple Preview. For about 8 of these 10 people, when I edit their text boxes and/or move them, Apple Preview immediately changes the text color of the red text to black, or to white. How do I get it to stop doing this? Is this a setting I need to have them change on their end? Or can I fix this on my end (preferable)?

Here is a link to such a file:

http://www.4shared.com/dir/rlemQEcJ/_online.html

When you try to move or edit the text "Sollazzo", it changes to black or white. I need it to say red. Thank you for your help!