Well, first of all, I would get rid of talking about scoops, cups, teaspoons, tablespoons and such. Most of us are not US based anyhow and let's face it, measuring powder using these units is very inaccurate. So get your kitchen scale out and measure those grams!
Then calculate the number of calories you need per meal using the Queal nutrition facts per 100g (the number varies a little bit depending on which variant of Queal you are using, but it is around 395kcal per 100g). And then experiment couple of times and find a proper amount of water (grams or milliliters) you like.
For me it is 150g(ml) water, 153g Queal Lite, 250g(ml) water. Shake. Meal. Rinse. Repeat.
I put little bit of water first to avoid powder sticking to the shaker bottom and edges.