Just got a notice from Amazon: Could be cool, I just wish there was a way that only I could do this, and not anyone with access to my Echo.
That is possible to only allow you, via a voice code, more info here: https://www.amazon.com/gp/help/customer/display.html?nodeId=201807230
Ya, im glad they did that, now just hoping that they will expand upon this. follow my feature request list I sent them and program in wake word speech authentication via speech enrollment. Then you could have multiple amazon accounts link to the echo and the ability to authenticate a user by wake word and the echo could know that persons amazon account and re-order or order items under that amazon account and not a global one like it is now. They already started on two of my feature requests IFTTT and traffic info (they need to expand both though).
Yeah I hate having to say "Which account?" and then "Switch account" if it is my wife's. They should either be able to use recognition, or your wake word idea.
I think they can based on the what I saw in the source code they have on the amazon echo site, amazon owns Ivona which is most likely how they get the text to speech (so changing the voice should be possible) and they have speech enrollment already in the app, just put it all together. It would make it more secure then having to say your voice code out loud.