I wish it worked differently. I wish the signature (and profile, too!) that posted in a message stayed the same for that message, always. That way people reading older posts will not see trailers the poster didn't own at the time. I mean, imagine posting about your particular trailer's quality (let's say Scamp) without actually saying what kind it is, because everyone sees it in your signature or profile; then, later on you get a new trailer (let's say Casita) and people who read that old post could easily think you were discussing the Casita's quality. That's just one example.
To every thing there is a season, and a time to every purpose under the heaven... --Ecclesiastes 3