It would be nice if each notebook could store a set of tools. This would be to select the 3 sizes that the application allows you and a series of colors for a specific notebook, that is, that the sizes are not modified in general, but only for that notebook. This could be implemented with a padlock-like button to lock the settings for that notebook only.
It would be great for when you import a pdf of a different size from the notebook you usually use and you want to write on that pdf.