The Macro Ratios setting calculates your macronutrient targets by dividing your energy target between protein, carbs and fat to achieve the ratio of macros you've entered. Any time your energy target changes, your macro targets will update automatically for you to keep your ratio of protein:carbs:fat. Your energy target will update throughout the day if you log exercises or log a new weight in your diary, for example.
Define a ratio based on energy (kcal or kJ) or by weight (grams).
The percent of energy coming from each macro is displayed beside each box. See the example calculation here to see how this works.