Setting the Default Script
Normally the target for any debugging session changes, tracking the package selected in the Project Explorer.
You can change this behaviour so that the scripts for a package remain selected in the Debug window. Use the context menu on the Scripts folder in the Debug window to either Pin or Unpin the currently-selected package.
When a package is pinned, the Debug window always displays the scripts defined for that package, and the debugger always uses the selected Package Script.