The solution is:
1. home screen settings
2. about home screen
3. app info
4. storage
5. clear data
6. clear cache
https://eu.community.samsung.com/t5/Smartphones-Tablets-Wearables/samsung-S7-oreo-update-home-and-apps-screen-reverts-to-defaults/m-p/563658/highlight/false#M20368