A package name is a unique identifier used by the device operating system to validate an app's identity. This is the key component in any of the app store's process for checking apps for updates, as well as assisting in creating additional values like app-specific user preferences and game save data. Unfortunately, we are unable to change your application package after your app is submitted to the Amazon Appstore.
Due to the nature on how device operating systems handle app package names, existing customers who have downloaded your app would be required to completely uninstall your app in order to receive the new update. Additionally, all saved user data for that app would no longer function, as that data is stored under the previous package name's user data folders. We strongly do not recommend that you change your package name, as this is a poor customer experience for your end users.
However, if you choose to use a new package name, you will need to create a new app with your updated package name. It's important to note that your current version's Binary file name is not the same as the package name. Binary file names can change from version to version, provided the underlying package name (determined through your app manifest or the respective build settings of other development tools such as Unity) does not change.