If a video's owner has turned on comments, you can post comments and like, dislike, or reply to other people's comments on a video. You can also edit or delete any of your own comments. Replies to a comment are threaded beneath the original comment so you can follow the conversation.
Post comments on a video
Public videos
All comments on public videos on YouTube are public and anyone can reply to a comment that you post. If you're a Google Apps account user, any comment you post on YouTube is publicly visible to users outside of your domain.
To add a comment, just type in the Add a public comment box under the video, then click Comment.
Private videos
Comments are not available on private videos. If you want to allow comments on a video that's not publicly available, post an unlisted video instead.
Unlisted videos
You can comment and reply to comments on unlisted videos. Comments on unlisted videos can be seen by anyone who has the link to the video. Learn more about unlisted videos and privacy settings.
- Click Reply beneath a comment.
- Type in your comment.
- Click Reply.
Add formatting to comments
Add style to your comment
You can use rich text to format your comment with common special tags, such as:
*bold text*→ bold_italicized text_→ italics-strikethrough text-→ strikethrough
Add links to your comment
If you add a URL to your comment, it will show as a hyperlink.
Add hearts to favorite comments
You can use a heart 
- Sign in to YouTube.
- Go to a Community tab post.
- Look for the
icon next to the thumbs up / thumbs down icons.
Viewers will see your avatar with a small red heart on the lower left and receive a notification (depending on viewer opt-in settings on desktop and mobile) that a channel owner "loves your comment."
Access to Discussion tab
The Community tab replaces the Discussion tab. Comments from the Discussion tab can be accessed in the activity log and will be available for 30 days after your account gets access to the Community tab.
To access the activity log:
- Open the YouTube app and sign in to YouTube.
- Go to www.youtube.com/comments.
You can pin comments to the top of the comments section to highlight what comment your fans see first when viewing your content. You can choose to pin your own comment or a fan comment.
- Sign in to YouTube.
- In the comments below a video, select the comment you want like to pin.
- Click More
Pin. If you've already pinned a comment, this will replace it.
Note: You can Unpin a comment at any time and the comment will be moved back to it's original position. - Click the blue Pin to confirm.
Pin. If you've already pinned a comment, this will replace it.Viewers will see the pinned comment at the top of the watch page with a "Pinned by" icon and your channel name.
Go to a comment, then use the Like 
Tip: If you see a comment that you think is inappropriate, you can report it as spam or abuse. If you're a creator, you can also use the comment moderation tools to manage comments on your videos.
- Hover over the top right of your comment.
- Click More
.
- Choose Edit or Remove this comment.