Click the Office button, and then click PowerPoint Options.
Click Trust Center. Click Trust Center Settings.
Click Trusted Publishers. Select a publisher, and then use the View and Remove buttons to make the changes.
Click Trusted Locations. Select a location, and then use the Add new location, Remove, and Modify buttons to make the changes.
Select or clear the Disable all Trusted Locations, only files signed by Trusted Publishers will be trusted.
Click OK.
Click OK again.