Open Customize dialog box (Tools, Customize) at the Toolbars tab. Check
Shortcut menus, which will make the Shortcut Menus toolbar appear on
screen. Now switch to the Commands tab of the Customize dialog box and
choose Insert. In the right pane, scroll down to the Comments command,
drag it to the Text menu on the ShortCut toolbar. When the menu opens,
drag to the Text submenu, and drop the command on that menu. You can
edit the menu button further if you want.
Now when you right click on text, the context menu that opens will
include the Comments command.
Larry