In order to enable Custom Grouping in Google Analytics Universal Analytics you need to:

- Go to the “Admin” panel is GA (1)
- Select the correct “Property” > “Account” > and “View” with your website data (2)
- Choose “Content Grouping” in the “View” column (3)
- Click “New Content Grouping” button in the next screen

- Give the grouping a name
- Click and enable the first section from the top (4)
- The index number you see below (5) is the one you should enter in Full Picture’s settings
- Save page

- If you forgot the index number, it will be also visible in the table with enabled custom groupings (6).