In this case, we need to change an existing `N' annotation into an `A' annotation. To do so, we must select the annotation to be changed. Annotations are selected by clicking left or right in the signal window. Whenever the pointer is in the signal window, clicking left selects the annotation to the left of the pointer, and clicking right selects the annotation to the right of the pointer. (If `Num Lock' is off, and the pointer is within the signal window, you can use the \Ovalbox{\small\sf $\leftarrow$} or \Ovalbox{\small\sf $\rightarrow$} keys instead of the mouse buttons if you prefer.) The annotation is highlighted by a selection rectangle drawn around it, and the pointer jumps to the center of the rectangle (see figure 2.6).
It is often useful, especially while editing annotations, to display marker bars above and below each annotation. If you wish to do so, click left on \ovalbox{\rule[-.3mm]{0cm}{2.5mm}\small\sf ~View...~}, then click left on the \Ovalbox{\small\sf markers} selection in the View window that appears (see figure 2.7), and finally click left on \ovalbox{\rule[-.3mm]{0cm}{2.5mm}\small\sf ~Redraw~} to dismiss the View window and redraw the signal window with annotation marker bars (see figure 2.6).
