If you are logged in, you can tell it that's your preference and it will remember.

I've tried, but I'll try again. I'm not clear what "logged in" means, I guess? It's using my android auto from my phone. Everything is authed against my google account, including my Gemini, presumably. Is there a secret Gemini/AA I'm missing?

That's interesting, maybe there's some limitation there. I haven't used android auto so I don't know whether it has access to an instruction file like the desktop application!