I utilize the open-source KeePass software to securely manage my passwords.
All my passwords are kept in a single .kdbx file that is end-to-end encrypted using a single, strong master passphrase.
I synchronize this file across my devices with Syncthing, but it's also compatible with cloud services, as KeePass can handle merges and conflicts effectively.
Additionally, I back up the file in my Trilium knowledge base.
For the master passphrase, I recommend to create a unique phrase that consists of multiple easy-to-remember words and is at least 30 characters long. For instance: "I love my very long and strong password."