Is there any way to change the default date range in the search function, so that the "Newer than" option is more than just 1 week?

We run technical support forums, and with this default a lot of people don't find what they're looking for (as they don't see the "1 week" part) and then end up taking more of our support staff's time asking a question they might be able to find an answer for easily if they had done a more extended search.

We'd sure love to be able to extend this default to something longer, if there's an easy way to do so.

Thanks!

Tracy