How to secure Password
First of all a password should be strong (long and unique) You should have a unique password for each and every account. Hackers are benefitted in a way that if one of your account is hacked meaning all are hacked. If possible try to keep different usernames too. Make sure your passwords are tricky and also long enough(suggested atleast 15characters) at the same time.
Second to make your password unique and strong it should be tricky You can use a mix of phrase, numbers and symbols arranged in a random order. You can also encrypt your favourite song line and keep it as password. Passwords should be hard to guess but easy to remember.
Third is use a Password Manager so that you are not resetting it everytime OnePass, LastPass, Bitwarden, Enpass etc.. Google and you will find many. I would recommend not noting it down in a notebook as there are high chances to sneek at your home by any of your close ones. Remember, If you lost your notes the passwords are also lost.
Last is to use a Two factor authentication Multi-factor authentication Or Two factor Authentication. This adds a one more layer of security on the verification process. This is also done sometimes by fingerprint or faceId on phones.
NOTE: All the above steps are mandatory before you decide to save your password.