Hi Linda,
Thank you for reaching out to Microsoft Community Forums.
From issue description, we understand that you want to change the direction of extended monitor to right side.
Let me go ahead and help you with the issue.
Which version of Operating System is installed on the computer?
I suggest you to follow the steps below and check if it helps:
a. Right click a blank area on the desktop.
b. Left click Personalize, Display settings.
c. In the Monitor window that opens you should see your two monitors. Find out which is which by clicking Identify Monitors.
d. Click and drag the right hand monitor left to the left of the original left monitor and release the drag.
That should change the positions of the two monitors so that the mouse motions should be the way you want them.
Hope this helps. If you have any further queries/issues related to Windows, write to us and we will be glad to assist you further.