Why does "Do you want to save changes?" appear only when I hit Alt+F4 by accident?

Alt+F4 closes the active window, so a save prompt usually means that app thinks something has changed. It doesn’t necessarily indicate a keyboard problem.

Choose Cancel first. That keeps the document open so you can check its title and app name. Look for an unsaved indicator such as an asterisk, although not every app uses one. If you’re unsure what changed, Save As a separate copy rather than overwriting the original.

If this happens only when you accidentally press Alt+F4, the shortcut is behaving normally. Windows doesn’t have a general “confirm every close” setting; an app-specific shortcut remap may help if it happens often.

If windows try to close when you press F4 alone, check whether Alt is stuck or latched through Sticky Keys under Settings > Accessibility > Keyboard. Testing another keyboard can help distinguish a physical key problem. If it continues, share the app name, Windows version, and the exact keys that trigger it.