Just say “Alexa, change the wake word” to each device for which you want to change the wake word. You can choose from Echo, Computer and Amazon. If you left your kitchen Echo wake word as “Alexa” and changed your hallway Echo wake word to “Echo” and your third Echo wake word to “Computer” then you’d easily avoid having your hallway Echo pick up Alexa commands intended for your kitchen Echo.
Thanks so easy.
Glad to help! 🙂