Name, tone, what it should try to achieve, and the things it must never do.
Under Chat & Voice Settings you decide who your assistant is, rather than what it knows. The phone assistant and the website chat are set up separately, on purpose — most businesses want a shorter, warmer phone assistant and a more detailed one on the website.
There is a "Write it for me" button that drafts the detailed instructions from what your assistant has already read. It only fills the box in — nothing is saved until you press Save, so you can read it first.
Every settings screen has a History button. It keeps what your settings were before each save, so a paste-over can be put back.
Because most businesses want them to be different, and many have no phone assistant at all. Changing one never changes the other.
Use the History button at the top of that screen. It lists what the settings were before each save and puts them back.