Xiaomi
Add an Account auf Xiaomi
Most apps create an account automatically the first time you log in, but some services - Exchange mail, a second Google profile, Mi Cloud - need to be added manually before they show up in an app. All accounts on a Xiaomi phone are managed from one central menu, independent of the individual apps that use them.
Where to add an account
Open Settings ➔ Accounts & sync ➔ Add account. Pick the account type you want to link, then follow the sign-in steps shown on screen for that provider.
Once an account is added here, apps that rely on it - Mail, Calendar, Contacts, or backup services - can read and sync its data without asking you to log in again separately.
When this does not help
If an app-specific login (for example inside WhatsApp or Facebook) fails, the fix is usually inside that app itself, not in Accounts & sync. Adding the account system-wide only covers services that support Android account sync, such as mail, calendar and contacts.
Removing an account from this same menu also stops all connected apps from syncing that account immediately, so double-check which services depend on it first.