Monetize your videos.
In order to start earning money on your videos, you’ll need to enable monetization. This means you are allowing YouTube to place ads in your video. This also means that you acknowledge that there is no copyrighted material in your video.
You can monetize a video as it uploads by clicking the Monetization tab and checking the “Monetize with Ads” box.
To monetize a video after it has been uploaded, open your Video Manager and click the “$” sign next to the video that you want to monetize. Check the “Monetize with Ads” box.