The Samsung Galaxy A8 (2018) is being treated to a new update currently. If you are a user of this unit, you should sit tight and wait for yours.
The version number of this update is A530FXXU2ARB9, and it is the security patch for the month of March. It also brings some fixes for bugs in the system as well as promises performance updates. The update is being pushed OTA. Being that it just commenced, it is understandable if it takes a while before it hits your unit.
We don’t know what regions the update is getting to right now but it is sure to reach all regions in a matter of time. Should you be impatient, you can head over to the settings menu and manually request the update.