no security product can cover 100% of the threat out there. However with a correct setup and good education you can avoid most of the potential issues.
Check you are not running vulnerable software, here. Be sure you are running the latest version of the ZA Security. Latest versions are published here. Every new version add new feature against latest threats. Then set ZA antivirus update frequency to lowest level (30 minutes). Just few minutes can make the difference between been infected and been protected
Ensure the ZA application control is the to MAX. Always mind about ZA popup windows warning you about suspicious behavior. Don't just allow everything without reading.
Under the Antivirus/Antispyware advanced settings, Ensure the "Behavioral scan" section, is checked. Under the Antivirus/Antispyware advanced settings, "Scan Option" section, ensure all riskware categories are selected.
Do not overlap security tool one over the other. It is likely to cause conflicts behind the scene with application fighting for resources and blocking each other. End result less security and difficulties in case of infections. Remove any other security tool you have installed to the exception of the free tools suggested here. Also ensure you have only one administrator account on your system and, as far as possible, use a limited user account for your daily activities on the PC.
Finally, if you encounter new non recognized viruses please send it in a password protected zip to newvirus at kaspersky dot com. Subject: virus. Include password in the e-mail. For faster response sign-up to kaspersky viruslab support at: https://my.kaspersky.com/en/support/viruslab and submit the file under the "Send request to Kaspersky Virus Lab" tab.
NOTE: the steps above works on 11.0.000.038.* or later. If you are not, please update.
* some custom settings may not be available in the free versions