Resetting a password is different than changing a password while logged into the user account. Administrator reset of a user login password creates a new keychain and thereby can disconnect user from services tied to saved passwords (email, website, etc.), and it is generally advised to avoid except if necessary and after exhausting other options. Can be sort of like breaking your car window because you cannot find your key. -rws
When a user resets their login password, macOS automatically creates a new login keychain to keep the account and login keychain passwords in sync. macOS archives the old login keychain so that if a user remembers the old password, they can unlock and access the archived login keychain items.
Importing keychain entries (if password is later determined), is a tedious process of manually importing (copy/paste) keychain entries one at a time. -rws
