Volvo 480 Club Europe

After a repair of a leaking driveshaft hose (gearbox side)
I tried to fill up the gearbox of this 2.0 ltr engine
It took me 1 hour to pour 1 ltr in
What am I doing wrong?
A small rectangle plastic box seems the only place to fill
Is there another quicker and easier method?

thats the breather pipe.fill it through a pipe in the level check hole on the front.

Thanks for the reply
I already notice the right spot, went to a Volvo dealer and
they showed me