Reusing the same password puts several accounts at risk when one service is compromised. A password manager makes unique passwords easier to handle.
Choose your manager
Look for a reputable manager that works on the devices you use and has clear recovery and export options. Protect the manager with a strong, unique master password and enable two-step verification when available.
Move accounts gradually
Start with your email account and other important services. Visit each service through its official app or website, change any reused password and save the new one in your manager. Confirm the new login works before ending your current session.
Plan for recovery
Keep recovery details somewhere secure that you can reach if a device is lost. Do not share your password vault using screenshots or ordinary email. Review unfamiliar login alerts promptly.
Further reading: NCSC: password managers.