Yes. I had a look through the manual before i posted but i was looking at a different spot and therefore did not see the paragraph you are referring to.
I finally found it on page 9: "The menu Hot-key will only work if the GSX Toolbar icon is Active ( icon is White
), because for performance reasons, all Javascript code in toolbar add-ons doesn’t
run when their Toolbar icon is Inactive ( icon is Darkened ), which means when
you start a Flight, you must first open GSX from the Toolbar icon using the mouse,
making the toolbar icon Active, which from now on will respond to the Hot-key
until the end of the Flight. If you close GSX using the Toolbar icon, making the
Icon Inactive again, you’ll have to open it again from the Toolbar before the Hotkey can be reactivated.
We suggest opening the menu from the Toolbar icon when starting Ground opera- tions, and closing it before Takeoff, since you will likely not need Ground services
until landing. This way, you can save a bit of performances, because when closing
the menu from the Toolbar icon, the menu code execution is immediately stopped.
Possible Key conflicts
It’s your responsibility to choose a combination that hasn’t been assigned to another
function in Flight Simulator. The Control panel can’t check this, so be careful not
to reuse a key that is used in the simulation, or by another add-on. However, even
in case of a key conflict, it won’t affect the simulation if the GSX Toolbar Icon is
Inactive, since no key interception can happen in that state."
This is between "GSX Hotkey Configuration" and "Passenger explanation". I expected this to be prior the first flight.
But nice that this has been sorted out.

thank you for your help!