I still believe you might have clicked that toolbar button by accident or hit some hotkey, although I don’t have KiCad at hand to verify if the choice is persistent or if there’s a hotkey for that. The symptoms are the same.
This FAQ article would have told how to clear the setup: Where are the configuration files (settings, library tables)?
KiCad itself doesn’t store anything in the registry. The installer may set some environment variables which are seen in the registry if you have chosen it to do so. When KiCad is running Windows sets some registry values related to KiCad but not KiCad settings per se.