iosiphonemobile-safari
I use a wifi hotspot where, after I connect, I have to fill in my username and password in a loginscreen.
My username stays the same, but the password changes quite often.
Safari used to detect when I entered a different password, and offer me to update my saved password. Now not any more…
How do I enable this?
As one can see you have the "Remember Networks this computer has joined" Enabled.
When you join new network, that information is saved in the
com.apple.airport.preferences.plist
located in SystemConfiguration folder.
Obviously iCloud gets that file.
EDIT
Since you asked a new question and want to know how iCloud does that read this. (and click on User defaults database to expand)
Designing for Key-Value Data in iCloud
To store discrete values in iCloud for app preferences, app configuration, or app state, use iCloud key-value storage. Key-value storage is similar to the local user defaults database; but values that you place in key-value storage are available to every instance of your app on all of a user’s various devices. If one instance of your app changes a value, the other instances see that change and can use it to update their configuration.
and
If you have a verified phone number and have set up the ability to verify devices using SMS verification code, you can use this method. Otherwise, you will not be able to recover your keychain yourself. You may find help by contacting Apple: http://www.apple.com/support/icloud/contact/
Best Answer
Go to Settings→Safari→'Passwords and AutoFill' and enable 'Name and Passwords'.