Corrine is having issues with her Apple ID. Leo says that her iCloud account and her iTunes account can be different. Or she could have them be the same. She'll then need to have a password that goes with it. All of her app and website passwords can be kept in the Apple Keychain, but she'll have to be on the same account in order for it to work across her devices. She'll have to be sure to go into her iCloud and Keychain settings and make sure they're all turned on.
Chris is having problems with the keychain password feature of his iPhone. He can't change the phone number associated with his keychain on any of his devices. Leo says that is a recovery feature that will send a recovery code via SMS to change his passwords. Leo says that second factor authentication is an important thing. If he has to get rid of the number, simply deleting it is what Apple recommends. They've also had trouble with keychain, though. Apple support may be needed and have them reset the keychain from their end.
Marie had someone set up her router, and she needs to get the Wi-Fi password to set up a new printer. Leo recommends taping a piece of paper with the Wi-Fi password to the router next time so she won't forget or lose it. She can reset the router by powering the router down or unplugging it, then pressing and holding the little reset button for about 10 seconds, then when she starts it back up she can configure the router. But this would require her to set up a new password and reset all of the devices connected to it.