Question about Kärcher RCV 3

Streaks on the floor tiles, do you have any tips? After he cleans with water and the cleaning cloth, there are streaks on the floor. We have tried warm water in the container, or even a drop of washing-up liquid (yes, we know you shouldn't do that): Doesn't help. If we clean it by hand, it's much better. At first it seemed a little better when we selected "maximum water supply", but the result is not great.