You may apply a new Custom Channel Group retroactively to organize data that has been previously collected.

  • True
  • False

The correct answer is:

  • True

Explanation: When you create a Custom Channel Grouping at the user level or create a new Channel Grouping in a view, you:

  • Can immediately select it in reports.
  • Can apply it retroactively and see historical data classified by your new channel definitions.
  • Change how reports display your data, without changing the data itself.

Read more here: https://support.google.com/analytics/answer/6010097