Originally Posted by
KARFA
I will add my welcome as well to you
tasso.asteriades 
Just to add that if and when you manage to update it on your profile, be aware this will not auto update the API held in existing bookings you have. You will have to go through each existing booking and update them individually with the new passport details I am afraid.
I also seem to have this problem. I have managed to update on API, not sure if it has stuck.
Trying to check in online for a flight tomorrow, I can check in but can't print boarding pass as it tells me my passport isn't valid. It's not valid because it is not updating with my new passport details! I've tried updating on ba.com and on the app, it appears to accept the update but still won't let be print a boarding pass as the passport isn't valid. I am going round in circles!