You can click here to change the default meals of the day in a meal plan (e.g. Breakfast, Lunch, Dinner, Snacks). Alternatively, follow these steps.
Step 1: Log in to Mealplana at https://app.mealplana.com
Step 2: Click on Settings > Customization
Step 3: Choose Nutrition Preferences
Step 4: Type in the default meals of the day you need, make sure to include only one entry per line. Changes are saved automatically