The data set tool in Cognos Analytics is a limited version of the Reporting tool. More recent updates to Cognos have expanded the functionality in Data Sets to allow developers to view and modify the queries behind the data set.
We can add new queries to this pane but one missing feature is a way to easily change the query the data source is pointing to.
In the Reporting tool, if I want to replace a query, I can go to the properties of the list and change the query to my new query. That property sheet is not available in data sets.
The workaround for this is to use the blue Reset button at the bottom of the data set. Then open the Data items tab of the Insertable objects pane and drag your new query's data items to the data set.
You can now remove the old query from the data set.
(This tip should work in Cognos Analytics 11.1, 11.2, 12.0).