Hello @Valerie283,
The "House rules" and "Directions" saved messages are editable only by going to the listing details page.
These are mdae available, by Airbnb, to guests who have a confirmed reservation.
This ensures that there's always just one set of rules and one set of directions given to each guest.
Of course hosts can change the rules and directions but it can be done only in the listing details so that all future bookings are made under the same rules and with the same directions.
It also avoids the possibility of a host specifying a rule or directions change in a message to one guest and then forgetting to update the rules or directions section of the listing.
From Airbnb's point of view the only enforceable house rules are the ones specified in the listing details so they're the ones that the guest receives automatically from Airbnb.
Steve.