1. Go to settings, select Audio; change sound quality (e.g. 'low' to 'ultra')
2. Restart as per recommendation.
3. Check Audio in settings; change successful.
4. Check visual quality (should have remained at 'low'); it is now changed to 'custom'.
5. Try this on many occasions, always the same result, e.g. visual settings change changes sound settings; sound settings change changes visual settings.