Never in this binder: a will, a power of attorney, advice, a password, an upload.
Not a will. For that, see a solicitor in the UK or an estate-planning attorney in the US. In the UK, MoneyHelper explains how wills work, for free.
Not a power of attorney. Nor a medical directive. The binder tells people where things are; it does not let anyone act. Only a lasting power of attorney (UK) or a durable one (US) does that, so make it while you can sign it. Wishes written in the kit are wishes.
Not advice. It isn't financial, legal or tax advice, and it won't tell you what to do with your money. It's organisation: getting what you already have written down and findable.
Not a password book. It never asks for a password, a PIN or a full account number. Nothing on paper should.
Not online. It lives on your shelf. Nothing to log in to, nothing uploaded, no copy anywhere but yours.
On every accounts page in the kit the line is printed in green: Never on this page: passwords, PINs, memorable words, security answers, full account or card numbers.