Once you've enabled community contributions, let your viewers know that they can help with reviewing and translating videos. Here's how you can raise awareness: 

• Share a link to a video: Let viewers know that you need help with a video and they'll be directed to the captions editor, where they can select the language(s) they can contribute.
• Share a link to your channel: Send viewers directly to a list of all available translations for your channel. They can review tasks for their languages and decide what to contribute.

YouTube determines viewers’ language profiles by looking at different factors, such as their interface language and watch history.

Get links to share with contributors

1. On a computer signed into your account, go to your Video Manager.
2. Select the video you want the community to help with. Make sure you've enabled community contributions.
3. Select Edit.
4. Select Subtitles and CC tab.
5. Under the video player, click the Invite your community to contribute to your video.
6. You’ll see two links: One for the video and one for your channel. If you don't see this, make sure that Community-contributions at the bottom of the screen is turned on. 
7. Copy and share the link(s) with your viewers. Try adding them to the video description or your social media posts to get more contributors.

Note: The channel link is also shown under Translations & Transcriptions > Community contributions. 

* Nguồn: Youtube