How to edit a post and count the number of posts in the header (Angular)?

Question

JavaScript

From everything, output and creation of a new one work for me, editing a post and counting the number of posts in a header do not work. When changing the quantity, it is said that the figure in the header should change synchronously - via @Input/@Output
Link to github
https://github.com/VHudzhal/jsadvancedtask8