Searching Criterias OR/AND joined?

Is there a way to specify whether my refined search criterias
are “AND”, “OR”, “OUTER” “INNER” etc. joined?

I’ve found out that withing standard parameters it is “OR”,
but withing keywords it’s “AND”. Different queues are "OR"
but narrowing 2 queues with one of their local keywords
is “INNER JOINED” (somehow) which never brings any result.

Is there a way to add an “Join” parameter in the search
Can I change it somewhere in the code?