but the basic is go through the php source files, firstly look for the files that you used to fill in the guessbook entry. there will be a FORM, submit to which page. follow to the next page section that process the entry... keep tracing this way, you will end up at a section that preformat the text before saved to database.
in worst case, they can happen after database entry, mean on the page that retrieve the entry from database. but this is very rare.
try the first step.
or the easy way, run the search for file content, look for the term 'thanks'. you will come to 1-2 files with that terms. get it open and modified. done.
I'd check with Dreamhost.com's support first. They should be able to help you with this if you want to modify it manually or maybe make an addon for you to do this if they provide this type of service.
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