When you refer to "... switched to auto ...", are you talking about the auto on/off function that turns the lights on as it gets dark, or are you talking about the auto high beam function that switches between dipped and high beam automatically? Your description suggested the former but maybe you actually meant the latter?
If it's the auto on/off function, then there shouldn't be any difference in brightness whether you've turned the lights on manually or have let the car do it's thing automatically.
But if you're saying that the lights are too dim when dipped but OK when the auto high-beam switches them to main beam, then it sounds like the beam setting is too low.