I have been a Kindle user since version two of the hardware.
Over the years, I have had a few different Kindle devices and installed the Kindle app on many iPhones, Pixels, and computers.
The Gripe
For those that don’t know, when you register a Kindle or use the Kindle App, Amazon creates a unique kindle.com email address so you can send content (outside of the store) to your device. Very cool.
The problem becomes one of maintenance of registrations. At present (after already removing several entries), I have 21 unique accounts!
Accounts are human-readable and increment by one: Kirby's Kindle For Mac, Kirby's Kindle For Mac 2, Kirby's Kindle For Mac 3, …
Oh, the kicker is that you can’t bulk edit the entries :-(
The Solution
During onboarding (installing on a new device), the app should prompt the user to find out if it is replacing an old device. It should automatically remove the old entry or transfer the old entry to the new device.
Update the Amazon web app to support bulk edits.
KISS