Once your channel has achieved the total number of required YouTube hours and number of subscribers, then you are ready to enable monetization on your videos.
Login to your YouTube account.
Click on My Channel in the drop down after you click on your icon in the top right corner of the screen.
From this screen, click on YouTube Studio.
On the bottom, left-hand side of your screen, click the option for Creator Studio Classic.
Once you’re in the Creator Studio, click on Channel > Status and Features. Finally, in the box that says Monetization, click Enable.
After you’ve enabled monetization on your YouTube channel, your videos can be submitted and approved for monetization.
In order to earn the revenue that is generated from these ads, you will need to associate a Google AdSense account accompanied with your YouTube account.
First, to qualify for monetization, your channel has to have at least 4,000 hours of watch time within the last year and at least 1,000 subscribers.