Hello, since I have recently also become the owner of a FAKTUM kitchen, I had the same problem with the wall cabinets, vertical, that the hinges did not stay at the top once the front was attached to them.
Solution:
At the lower end of the hinge there is a narrow slot above which a " " is embossed. Above this slot there are three vertical slots in which an adjustment screw is visible. Above this is a "-" embossed. In this narrow slot there is a hole in which apparently a screw can be seen. However, it is not a screw, but rather a gear.
As shown in the enclosed instructions, you must now insert a suitable Phillips screwdriver into this narrow horizontal slot (below the embossed " ") into the hole. Then simply turn the screwdriver clockwise (to the right) and observe the change of the adjustment screw. Then adjust both hinges the same way.
Have fun.