Your starting weight should already be entered during the sign up process. However, if you need to adjust it, just go to the app footer and tap on Profile > Manage Profile > Update.
It is important to be accurate with this weight when you first start! Overestimating or underestimating your starting weight will change your macros accordingly. Please note that this is not a goal weight entry either. This is the weight you are currently at before you begin your first Fat Loss, Maintenance, or Muscle Gain phase.
As you move through your Fat Loss, Maintenance, or Gain plan, you will not need to update the starting weight. The reason for this is that if you are seeing progress, then the macros you have been given are working as is and we want to keep it that way! Updating the starting weight will change those macros. If you do reach a plateau on a certain phase, you can always move to the next phase. For information about when to move to the next phase, click here.