The second section of the notation panel, is similar to the first one but in this one the litte "keyboard" made of select boxes contains the note names.
You can click on each of them and select how you want to display that note.
For example you can choose to display all the A# as Bb or even a G as a double sharp F or double flat A.
Once you select a name for the note the settings will be applied to the whole document.