How to change National insurance number?? it's Not letting me!!! help!

my parent's household income form online is finally complete, but they want to double check their NI, however i don't know(nor do they) how to get back to that section.I;ve looked through all the sections,and the NI box is not coming up.

How do you go back to the Ni number section?? What to do ?
thanks

Ask them to phone SFe.

If it's incorrect they will need to send proof of their Nino via post to get it updated(can't be updated/changed by advisor on phone)