Android
Turn Gboard Auto-correction On or Off auf Android
Auto-correction on Android runs through Gboard, the default on-screen keyboard on most devices. It compares every word you type against a dictionary and swaps in what it thinks you meant, based on nearby letters and common phrases.
That works fine for typos, but it also rewrites names, slang, and technical terms it does not recognize. The result is a message that says something different from what you typed, often sent before you notice the change.
You control this behavior in the keyboard settings, not in the messaging app itself. Open Settings ➔ System ➔ Keyboard ➔ On-screen keyboard ➔ Gboard ➔ Text correction, then enable or disable Auto-correction.
Turning it off stops Gboard from changing words automatically, but it also removes the quick fixes for genuine typos. If you only want fewer wrong swaps, watch the suggestion strip before sending instead of disabling the feature completely. Two related toggles in the same menu, Personalized suggestions and Show suggestion strip, also affect how aggressively Gboard predicts and replaces text.