Update: Switch Your Existing Campaigns to Core Search Only

By default you’ll see that Adcenter has opted you into “All Bing and Yahoo! search networks and syndicated search partners” for your existing Adcenter campaigns.
To change this setting in the Adcenter online UI:

1. Drill into your campaign and check the box next to “Adgroup” to select all of the adgroups in that particular campaign.
2. Then click the “More” button and select “Bulk Edit”
3. From the drop down selector box in the blue area choose “Distribution to Networks” and you can bulk edit your adgroup’s search configuration.