How to Better manage passwords
Your keychain
Go to Settings > Passwords & Accounts. The top item shows the number of credentials you’ve saved to your keychain. Tap that row to check you haven’t used any password in two places, which is a security risk.
Warning icon
After authenticating with your passcode, fingerprint or face, you’ll see the list of credentials. Depending on how secure your password is you may spot a triangle, indicating iOS’s opinion that the password isn’t secure enough.
Change password
Tap on a password that displays the alert triangle and you’ll see an option to change that password on the relevant website; iOS guilts you into action by indicating how many times you’ve used this password, and where.