Homepage content and page selection

Hi, me again.
I have been trying to link my little 4 boxes to posts instead of pages…
I changed data from pages to posts (I don’t know how to put the both for choice) which is fine.
But, the select form only proposes the 5 latest posts. I am unable to select my first post. How come?
Would you mind helping me to understand where I can make that changes.
Thx in advance.
Made.