Realme
Change System Language auf Realme
The system language on a Realme phone is usually set once, during the initial setup wizard, based on the SIM region or a quick selection screen. If that choice was wrong or you simply want a different language later, you don't need to reset the device to factory settings.
Realme UI keeps this option separate from the general display settings, inside the additional settings menu. Go to Tap on Settings ➔ Tap on Additional settings ➔ Tap on Language & region. From there you can add a new language and move it to the top of the list, or switch directly if it's already installed: Tap on Add a language or drag a Language to the first position ➔ Tap on Change to....
Moving a language to the first position tells the system to use it everywhere, including menus, notifications, and most pre-installed apps. Third-party apps that ship with their own language files may still fall back to their own default until they sync with the new system language.
A factory reset is only necessary if the language mix-up happened alongside other setup problems, such as a broken account sync or corrupted settings backup. For a simple wrong-language situation, the Language & region menu is the correct and faster fix.