Thank you for sharing your question about your granite benchtop.
I suggest using Glitz 750ml Stone And Benchtop Cleaner. It is specially formulated for the cleaning of granite, marble, and reconstituted stone surfaces. I recommend having a closer look at the white stains, are they embedded into the stone or are they paint stains? Acid-based cleaners often damage the finish and seal of the stone top. If they prove to be too tough and do not come off with regular cleaning, I suggest engaging the services of a professional stone polisher to clean and seal your top again.
If you need more advice or information, please let us know.