Hi,
If you're trying to change which account is the active save Destiny 2 characters, you will need to disable cross save, wait the time period, and then re-enable cross save with the correct character set.
If you're not able to authenticate and login to all accounts associated with your cross save setup (to disable cross save), then you have two options : 1) Work with the platform support to troubleshoot getting access to your account(s) involved OR 2) Your account is stuck as-is and you will be unable to edit any cross save settings.
More information in the [url=https://help.bungie.net/hc/en-us/articles/360049498031-Destiny-2-Cross-Save-Guide]Cross Save Guide.[/url]