You can modify your settings by clicking on the "Settings" button on the home page. The "Scan Settings" tab can be used to specify filter exclusions based on file extensions. You can use the + or - sign to add or remove the filter content. You can also specify a file size range for minimum and maximum size.
To add a new filter click on the + sign as shown and enter the content type and then add the extensions. Extensions should be seperated using a comma.