Input showing up in all repeated cells, only want it in the selected cell


I have repeated ‘post’ containers in a newsfeed style page, and within each of these posts there is a comment input bound to a single page variable. When typing in a comment I want the rest of the comment inputs to stay with the default value ‘Add a comment…’ and only the comment input that was pressed to show the input text. Currently when a user starts typing a comment it shows up in the input box for each of the posts, and the newsfeed can have many repeated posts.

Any advice on how to fix this would be greatly appreciated!