Change Account name in Quicksight

Based on the AWS QuickSight documentation, the account name cannot be changed after it has been set during the initial QuickSight subscription setup. The account name is created when you first sign up for QuickSight and is unique across all of AWS. This name appears when users sign in and is part of the QuickSight URL structure.

Unfortunately, there is no API or console option available to modify the account name once it's been established. The account name is a permanent identifier for your QuickSight subscription within your AWS account.

However, the good news is that this limitation shouldn't affect your work. All existing Datasets, Analyses, and Dashboards will remain intact and accessible regardless of the account name. The account name is simply an identifier in the URL and sign-in process - it doesn't impact the ownership or accessibility of the QuickSight resources you've created.

If changing the account name is absolutely critical, the only option would be to create a new QuickSight subscription with the desired account name, but this would require migrating all your existing work to the new account, which is likely not the solution you're looking for.

As an alternative, you might consider updating user names or adjusting permissions and roles within QuickSight to reflect the current ownership structure, while keeping the original account name unchanged.
Sources
AccountSettings - Amazon Quick Sight