By default, the left button is the primary button of your mouse in Windows 10.If you wish, you can change primary button of your mouse at any time you want and here is how: angle-right Open Run Command Box. Type "main.cpl" (without double quotes) and then press "Enter" key. angle-right Now, in the "Mouse Properties" popup, you can see "Switch primary and secondary buttons" option. Select it. Keep in mind that the changes are immediate and now your primary button is right button. angle-right Hit "OK."If you want to go back to default, then unselect "Switch primary and secondary buttons"