Search Logic

Can’t seem to quite understand the search logic.
For example, I search for:

1740 Sunnydale Ave

And the first contact the comes up, shown as 100% search score, was found because her last name was “Ave”
I’ve tried plus signs between the words, quotes, and more.
Is there a document that explains how to search, how search results are rated, and the Advanced Search/Basic search differences?

Currently, when there’s a single search bar (what I THOUGHT was the basic search, there’s a “Use Basic Search” link above it.
When I click it, I get a screen asking me what modules to include (note that this PO box appears in the address of one account):

Thank yoU!