Please click on In order to create an item, please tap on Profile on the bottom tab bar on your Diary page and then on the round gear symbol to the left at the beginning of the page. Your Settings are here.

After that tap on Personal Details under Settings. To change your calories per day goal, tap on Calories / day and overwrite the given value. Save the new number by tapping on 'Save'.

Alternatively, you can, of course, always change your goal by going to In order to create an item, please tap on Profile, then on Goal ,and then choose a new goal. There you can start the goal setup with all details from the beginning.