On the Tools menu, click Customize.
The Customize dialogue box is displayed.
On the toolbar in the main window, right-click on the image you want to change.
Click on the Button Appearance... context menu item.
The Button Appearance dialogue box is displayed.
Select Select User-defined Image.
Click on a new image, or create a new image by clicking on the
New... button.
Click OK on the Button Appearance dialogue box.
Click Close on the Customize dialogue box to return to
text editing mode.