- Enable TrueView in Advertiser settings
- Enter the channel code in Advertiser settings
- Link the YouTube video
- Link the YouTube channel
The correct answer is: Link the YouTube channel
Explanation: By linking a YouTube channel to a Display & Video 360 advertiser, you can use an expanded set of features for TrueView and bumper campaigns, as well as gain insights into your traditional linear TV campaigns with a TV Ad Explorer.
Read more here: https://support.google.com/displayvideo/answer/6273819