Go to System Prefs, then Displays, then theres an option between Display and Color (maybe Appearence, I don't have my other monitor setup). From there, you can adjust whether each screen is to the "right" or "left" if you drag the monitor boxes around. Also, you can move the top bar from one screen to the other by moving the thick bar at the top of one screen to the other, between the boxes.
Go to System Prefs, then Displays, then theres an option between Display and Color (maybe Appearence, I don't have my other monitor setup). From there, you can adjust whether each screen is to the "right" or "left" if you drag the monitor boxes around. Also, you can move the top bar from one screen to the other by moving the thick bar at the top of one screen to the other, between the boxes.