"Currently, Goodnotes does not have a specific feature that automatically sets the toolbar to start on the Pen tool when switching between files. The Pen tool is the first tool in the Handwriting Toolbar and can be selected manually, but the app does not remember or default to the Pen tool automatically upon file switching," Goodnotes Support.

It would be great if a toolbar customization update allowed you to make the pen feature the default tool when switching between documents instead of the lasso.