A new Custom Channel Group may be applied retroactively to organize data that has been previously collected.

Channel Groupings are rule-based groupings of your traffic sources. 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. Tip: If you have Edit access at the view level, you can promote one or more of your Custom Channel Groupings from the user level to the view level.