Centre arm rest will not stay closed, there is a real easy fix involves super glue and 6 small Neodymium magnets at the front of the arm rest base you will see a slot that the top alignes with glue two magnets to the left of the slot and two magnets to the right.Do this separately waiting for the one set to become firmly glued down otherwise as you put in place the second set they will pull the first set away unless they are really set.
Next glue one magnet on the sliding top at the front and wait for glue to cure once set glue one further magnet to the top front so that they align once top is slid in place.
Make sure that every thing is set well and then replace top into the slides.the magnets have a .75kg pull so no more nuisance opening, magnets cost around 2 dollars for a pack of 10 available on ebay.

 

That's a very creative solution to this poorly engineered arm rest.