Choose Numbers from the Display menu. Select Bar from the submenu. This brings up the Bar Numbers dialog. Here you can change the way bar numbers are displayed in your score.
Choose to never display bar numbers, display them every line or every bar by selecting Never, Every line, or Every bar in the Show Bar Numbers section of the dialog. You can start numbering from the first bar or the second bar (do this if your first bar is a pickup bar) by selecting First bar or Second bar in the Start Numbering From section. Finally, you can position the bar numbers above or below the staff by selecting Above Staff or Below Staff in the Position section.