Using the drop-down list, you can migrate from one antivirus solution to another (ClamAV or Advanced antivirus). When the antivirus is chosen, the following message will appear:
"The antivirus database has to be fully downloaded before the antivirus can be changed. During this interval, the antivirus scan will fail.” Click on Switch engines to confirm your selection.
Once the database has been downloaded, the antivirus will be enabled.