Samsung
Turn On Automatic Backup to Samsung Cloud auf Samsung
When photos, messages or app data are missing after switching to a new Samsung phone, automatic backup was likely never turned on for that category. Samsung Cloud only backs up what you explicitly allow under Auto back up, and this setting is separate for each data type.
To enable it, go to Settings ➔ Samsung account ➔ Samsung Cloud ➔ open the Menu ➔ Settings ➔ Sync and auto backup settings ➔ Auto back up. From there, turn on the categories you want backed up automatically, such as contacts, photos or app data.
Once enabled, Samsung Cloud backs up the selected categories on its own schedule, usually while the phone is idle, charging and connected to Wi-Fi. Turning a category off stops future automatic backups for it, but does not delete backups already stored in the cloud.
If storage runs low or you only need a one-time backup, a manual backup through the same Samsung Cloud menu is faster than waiting on the automatic schedule. Automatic backup makes more sense if you regularly switch or reset devices and want data protected without extra steps.