After running a test of the traffic, you can choose to block sources that are not yielding the desired results.

Click on the name of the campaign you want to edit. A statistics page opens. You can see all the sources that sent you traffic.

You can turn the green dot mark next to each number to red. This means this source will be blocked from your campaign.

It's important to double check that the sources you selected are updated in the Managed Blocked sources tab located above the sources list.

You can also block sources manually by clicking on Manage Blocked Sources. Insert manually each source on a separate line.

Please note that Blocked sources may take up to an hour to update and reflect in statistics.