I manage my passwords and login credentials for more than one web server by using a secure and centralized password manage like Bitwarden or KeePass, which allows you to store unique, random passwords for each server you need to login to.
You can also use SSH keys, central user management "LDAP/AD". or secrets managers like AWS Secrets manager, HashiCorp vault etc to eliminate the need for manual credential sharing and enhance security of your servers.
I also keep a copy of my passwords and server information printed on a paper in a locked filing cabinet as well as on thumb drives that are marked with the login details to the servers.
I keep multiple backups of the login details for the multiple servers to be able to login to them.
I used to forget passwords and login details to servers and after storing passwords and login details to the servers in multiple locations including on paper, I haven't lost access to the servers since.
Using password manager tools like Keepass, "offline, file based" or Bitwarden/LastPass which is cloud based to store your random passwords, ensures that no reuse can occur across servers.
You can also disable password based root login for your servers in favor of SSH keys.
And a single password protected key file can also allow you to access multiple servers and offers high security and convenience.
Using LDAP or FreeIPA to manage user accounts across servers also helps and enables consistent authentication and role based access control.
For larger setups, you can use HashiCorp Vault for managing login details for more than one server, or use AWS Secrets Manager or Azure Key Vault to manage your credentials, API keys and sensitive data security.
Using password managers that also support "equivalent domains" like LastPass, Keeper, to manage multiple web interfaces can also help.
I also store my login credentials to multiple servers on cloud storage after encrypting the files.
This also allows a backup for the passwords and login details.
Even the database and website files are also backed up in the cloud as well as on thumb drives and external hard drives in the event I need them so I can easily restore the website.