Hi. Tbe design isn't poor, but I think your understanding of it may be.

The account is linked to a system, not a user. You could not possibly have logged info your account when at your father's, because the only speakers and system there are his. The Sonos app is just a remote control and can connect to any system, once it is on the same subnet.

So, to your current problem. Has any of the speakers you have at home ever been part of your brother's system?

Which speakers do you have at home?

No, they’ve never been as far as I’m aware, although I can’t promise he hasn’t used them before so maybe something was changed then. Just weird that it suddenly happened out of nowhere? Either way, I now have no idea how to change it. They’re play1 so quite an early version. 

I suggest you try connecting with just one speaker powered on at a time. Try each one in turn until (hopefully) you find one that belongs to your system.  That is, the log in requires your email address. 

My best guess is that one if the speakers belongs to your brother's system, and that is the one that the controller is currently latching on to.

I cannot be sure of that, though. If you locate a speaker that still belongs to your system please post back for further guidance. 

You are talking about Sonos accounts here? Or Spotify or other music service accounts?

@naomip Go under App Preferences and tap Reset App and close and re-open the app and see if you can reconnect to your account.

Thanks both for your help!!! I reset the app and then reset each of the speakers and I was able to set up again - very happy. 

Hi.  I normally try to avoid resets of speakers until a last resort, as it means losing playlists, favourites etc.  Obviously that matters more to some people than others, so if you are happy that’s good.