This is best achieved using a filter rather than a sort.
To filter by resource:
- Switch to the "Tasks" tab
- Click the top half of the "Quick Filter" button
- Click the "[…]" button next to the resource field
- Pick the resource you first want to filter by
- Click "OK"
- Click "Apply Filter"
You can continue to work with your map while the "Quick Filter" dialog is displayed which means you can work with the actions for Resource A, then return to the dialog, select a different resource and apply that filter and so on.
Click the Top Half of the Quick Filter ButtonClick the [...] ButtonPick Resource to Filter ByClick "Apply Filter"