To gain more control over how Microsoft Security Essentials handles detected threats, use the Default actions or the Threat handling tab, depending on your product version.
Click the Settings tab, and then select the Default actions tab.
Select the action that you want to apply to each alert level (Severe, High, and so on).
Select the Apply recommended actions check box, and then click Save changes. If you're prompted for an administrator password or confirmation, type the password or confirm the action.
To learn more about applying default actions, see Applying default actions to detected items.