How do I select multiple notes at the same time?

To select multiple notes, you need to drag a selection box around the desired notes.

First switch to selection mode 'CTRL + 1' and then draw a box around the notes that you want to select. Alternatively, you can hold down the CTRL key and use the mouse to select any notes.

The notes are then marked in red and can be deleted (DEL) collectively or can be edited.