Search results controlled by “Reading Options” — How do I return all posts?

I am using the Andreas01 theme. Currently, when I search using the search widget, only 1 day’s worth of posts appear. This corresponds to the Reading Options, which I have set to 1 day. (I have tested other values here and determined that there is indeed a correlation.) I’m new to WP… I assume there is a way to return ALL search results (no matter their age). How would I do this?

I tried the Search Everything plug-in, but it didn’t change anything.

My blog is at acsaction.org.

Any help would be appreciated. Thanks!