1. Click on Start,
2. Choose Control Panel,
3. In new open window double click on Mouse icon,
4. In Mouse window you will see "Button configuration",
5. Check or uncheck "Switch primary and secondary buttons"
Note: If it is uncheck you are using left mouse button like primary and right like secondary, but if it is check you are using right mouse button like primary and left like secondary.
6. After you check or uncheck that field press OK.
