Each section’s keyboard shortcuts correspond to a row of keys on your keyboard:
If a section has more tools than the row of keys on the keyboard, the extra tools can be accessed with the SHIFT key. (E.g. SHIFT + Q, SHIFT + E, etc.)
A fifth section with the color gray will appear for some tools such as Note and Rest. This section is used to select which voice the tool will work on. You can also use the shortcuts ALT + 1/2/3/4 (Windows) or OPTION ( ⌥ ) + 1/2/3/4 (Mac) to select the voice you want to work with.
To cancel the creation of page elements that span multiple notes, such as beams, slurs and tuplets, or to clear note selection, either press ESC or simply select another tool.