>>2It's an image board meme. 4chan puts (You) on a post where your post is being quoted. It looks different for every user, since you only see the (You) posts for your posts, and other people see it on posts where their posts are being quoted.
Some people mention (You) in the context of people seeking attention. As in, ``here, have a (You)''
Do you remember the ``please respond'' meme on /jp/? I browsed /jp/ many years ago and it was basically the same concept, only there was no (You) back then.
>>1 is clearly saying they come here to get attention and replies.