Open the Campaign Performance screen and click on the Campaign name you wish to enable ad level CPC for.
Click Edit to open the Edit Campaign screen.
Check “Enable Ad Level CPC” and click Save at the button
Click on the Content tab from the Campaign Manager screen. You will now see “Edit” in the CPC column. Click the link to edit the CPC for each ad.
NOTE: Changing the CPC of the campaign through the scheduler does NOT change the CPC at the Ad level.