The Macronutrient breakdown is found next to the Energy Summary on the Diary page.
To change your Macronutrient targets, navigate to the More tab > Targets + Profile. Learn more in the article Macronutrient Targets.
The percentages listed within the Macronutrient Target bars indicate the percentage of your goal for each macronutrient. By default these bars will show your macronutrient breakdown for all items logged in your diary.
To see the macronutrient breakdown of a specific food or multiple foods, tap on the specific food or foods in your diary. The Macronutrient target bars will update based on the food(s) you have selected. To revert back to complete day breakdown, click on your selection again or click elsewhere in the diary screen.
Tap on Consumed in the top right to switch to Remaining. This will show how many calories and macros remaining you have based on your daily targets.