iCloud Security Questions

I am trying to create a new iCloud account. This requires me to enter security questions. I normally have no issue with this, but I am offered only 6 choices, and frankly I don't know the answers to any of them.

E.g. one asks for the name of my favourite primary teacher. None of them were, and I don't remember the names after 55 years.

How do I enter my own questions, which is what I normally do.