Volkswagen Golf GTI 2016 Owner's Manual page 407

Always remember: Even though your vehicle is equipped with an
Advanced Airbag System, all children, especially those 12 years
and younger, must always ride in the back seat properly restrained
for their age and size.
Activating the switchable locking feature
Slowly pull the shoulder belt portion of the safety belt all the way
out of the retractor.
While keeping your weight on the child restraint, guide the
shoulder belt portion of the safety belt back into the retractor until
the belt lies flat and is tightened against the child restraint.
You should hear a clicking noise as the belt winds back into the
inertia reel of the safety belt retractor. Test the switchable locking
feature by pulling on the belt. You should no longer be able to pull
the belt out of the retractor. The switchable locking feature is now
active.
Pull on the safety belt to make sure the safety belt is properly
fastened and tight.
Check the child restraint for proper installation by pulling on the
child restraint at the place where the vehicle's safety belt goes
into the child restraint. The child restraint should not move forward
or sideways by more than about 1 inch (2.5 cm).
After checking to make sure that the child restraint is properly