A strong password is not a random mess you will forget by tomorrow. It is long enough to resist guessing and personal enough that you can rebuild it when you need it. Short passwords with one symbol at the end are easy for programs to try. Long phrases are harder and easier for humans to use.
Think of a short story only you would invent. Choose four or five ordinary words that do not appear together in a song lyric. Example pattern: color, object, place, action. You can change spelling slightly or add a number that matters to you but is not your birthday posted on social media.
Use a different password for email and banking than you use for shopping or news sites. If one site is breached, the others should not open with the same key. A password manager helps, but even without one you can keep a private pattern and vary one word per site.
Turn on two-factor authentication wherever it is offered, especially email. A code on your phone blocks many attacks even when a password leaks. Store backup codes offline, not in a public notes app.
Change a password when a service sends a real breach notice or when you shared it by mistake. Changing every password every week is exhausting and usually unnecessary. Focus on the accounts that hold money, identity, or the keys to everything else.