Facebook changes the way it shows you news
The new system behind Facebook now only shows you roughly 20% of the actual posts made by your friends.
There is a complicated algorithm involved in what you actually will see.
The process involved gives each news piece a “score” and the higher the score that the system gives it, the higher up in your feed it will show.
Scores are determined using a number of factors, such as the relationship you have with the user who posted it, the number of comments, the number of shares, and the number of likes that the story has accumulated.
Previously, each time a user refreshed their feed, new stories automatically moved to the top of the feed — even if they had a lower score than stories previously displayed. A change in the ranking process now enables older stories (stories that may have been posted earlier in the day but the user never actually scrolled through) to join the “new” stories at the top of your feed.