View and update a client’s macros

From your 'My Hub' page (please see below)

On the left hand side of your account, you will see the side menu in which you can select 'Contacts'.

Select a client profile

and click on 'Assignments' from the list below the client profile picture followed by 'Nutrition Plan'

If you hit the 3 horizontal grey dots to the right of any nutrition plan and select 'Edit' 

You will see the assigned plan along with 'Macronutrients' which you will be able to edit.

Just remember to click 'Save Plan' once changes have been made.