Hi! When will be added this kind of button or how to create it?
Edit button for what?
You will need to do that on your own or hire a programmer. You can do that here: https://developers.oxwall.com/market/specialists
+1 to Chris's point. Point of newsfeed is giving an accurate and fair information that can not be changed. Treat this like a Twitter stream. What is posted is posted. If you want to change anything, delete previous content and generate a new one.