Oppo
Change Google Backup Account auf Oppo
Coloros ties Google backups to whichever Google account you select inside Back up and reset. If you added a second Google account later or want backups to land on an account with more free storage, the phone keeps using the old one until you change it manually.
To switch the destination, go to Settings ➔ Additional settings ➔ Back up and reset ➔ Backup accounts ➔ Choose an Account. Only Google accounts already signed in on the device show up in this list, so add the account under the phone's Google settings first if it is missing.
Switching the account does not move or merge existing backups. Files, photos, and app data already stored under the old account stay there and remain accessible if you sign back into that account later.
Only the next scheduled backup will run against the newly selected account. If storage space is the real issue, it is often faster to just clear space on the current Google account or upgrade storage rather than migrate everything to a second account.
Side effect to watch: restoring a new phone pulls data from the account it is signed into, so if backups are spread across two accounts, some app data or call history may be missing after setup unless you sign into the right account first.