Samsung
Change Google Backup Account auf Samsung
Samsung phones only back up to one Google Account at a time, even if several accounts are signed in. If a new account was added after the first backup ran, the phone keeps saving data to the older account by default. That mismatch is the usual reason backups seem to disappear or show up under the wrong Google profile.
The backup account controls where photos, contacts, call logs, app data and device settings get stored through the built-in Samsung backup service. Switching it does not delete existing backups tied to the previous account; it only changes the target for future backups.
Menu path to switch the backup account
Tap on Settings ➤ Tap on Accounts and backup ➤ Tap on Back up data ➤ Tap on Account ➤ Choose a Backup account
Pick the Google Account that should receive future backups from the list. If the account you want is missing, add it first under Accounts and backup before repeating the steps above.
Changing the backup account is the right fix when data lands in the wrong Google profile. If backups fail entirely, check the storage quota on the selected Google Account instead, since a full Google Drive can block new backups regardless of which account is active.