You can make changes to all existing queries, including the defaults. Any changes you make to the default queries are saved separately. You can delete these changes but you cannot delete the default query.
Open: Workspace Designer > Content Part Designer > Query Editor.
To save your changes, click Save All. This saves changes to all queries not just the one displayed.
The query is now saved but is not used in any workspaces at this point. This allows you to review your queries first.
Those queries that are saved but not yet used in workspaces are stored in the folder ...Sage\IM Content\Modifications\Queries\Pending.