Why are some of the pencils in my agent red?
Inside the advanced configurations of an agent you will notice there are pencils to the right of any sources the agent tracks. This is the button to click on if you would like to edit the source and the query that is applied to that source.
Most of the time you will see only yellow pencils, but depending on how you have configured your sources you may see some red pencils.
The red pencils indicate that this source does not use the same query as the agent.
What is the advantage?
You may find that one of the sources tracked by your agent is creating more noise that the other sources, but you don't want to remove it completely from the agent. You can click on the pencil and then edit the query for that source individually.
In this way you can tailor your [source + query] combinations to meet your needs.