Most of the text in the tables are assigned in the $LANG file. You just have to look to find in between the quotes. I would save a copy before doing any editing, to be on the safe side. I just "customized" one to make it a feedback location for the site I'm doing. You can look at it here if you like.
Look in LANG folder, pick whever you are using (probably english.php). line $LANG["BookMess6"] "XXXXXXX"; is where it is at. It also effects the text (in bold type) above it.