Samsung
Change System Language auf Samsung
Samsung usually sets the system language automatically during the first device setup, based on the SIM card region or a manual choice made at that point. If the wrong language got selected, or your language needs change later, you can switch it again without any data loss or factory reset.
The system language controls menus, system apps, keyboard suggestions, and voice assistant defaults. It does not affect photos, contacts, or installed apps, though some third-party apps may switch their own language automatically to match the new system setting.
Menu path to change the language
Open Tap on Settings ➔ Tap on General management ➔ Tap on Language ➔ Tap on Add language or select a Language ➔ Tap on Apply.
If your target language is not yet on the device, use Tap on Add language first, then select it from the full list and confirm with Tap on Apply. The phone applies the new language immediately, no restart required.
If only certain apps show the wrong language while the system itself is correct, check that app's own in-app language setting instead, since some apps manage their language independently from Android.