Re: How to change email and password on older Roku stick.
To change email you need to do factory reset. But if its too old of stick like 3500, and you are only using phone app, it will become a door stop. And once you do a factory reset it will lose pairing with its remote, so one of the first you do when the roku is bouncing start pressing and holding the pairing key in the battery compartment, release for a sec when roku stops bouncing and start pressing again until you get a confirmation that's its paired.
As @Tivoburkee mentioned, if you would like to connect your older Roku Streaming Stick to another account, you would need to perform a factory reset on your device. Once your device has been reset, simply activate the device using your newer Roku account.
Please be aware that factory resetting your device will reset all settings and return your Roku device to a state ready for initial setup, so it will no longer have the channels that were previously on it. When connecting the older Roku Streaming Stick to your newer account, it will have the channels that are currently linked to that account, as long as the device supports the channel.