1) Click 'Payment Options' under the 'Commerce' heading of the Control Panel.

2) Under the 'Security Settings' heading, edit your 'Payment Security Settings'.

3) When you are finished, scroll down & click the 'Save' button.

Updated
1) Click 'Payment Options' under the 'Commerce' heading of the Control Panel.
2) Under the 'Security Settings' heading, edit your 'Payment Security Settings'.
3) When you are finished, scroll down & click the 'Save' button.