Maybe there needs to be a way to set up regular auto-backups to your local machine (or regular prompts for manual backup), then import history into your new accounts on other servers.
Edit: also there should be a way to change which instance is your “local” for the homepage, irrespective of which one you actually log in to.
Long press on the empty space to the right of the username.
How were you supposed to know this? Magic, clearly. 🙃