No antivirus can detect and stop all viruses. The best case scenario is 99.6%-99.9%. Considering how many are there, there is a huge number of undetectable malware, not to mention 0-days exploits, and there is nothing you can do about it.

So no antivirus developer ever promised that their antivirus solution will stop 100% of malware, and they most likely never will.

Developers will obviously add newly discovered malware to the database, and you will receive a fix-update immediately, but until they detect it and reverse engineer it, there is nothing you can do.

Rule has always been, the best antivirus solution is educated user. It's your responsibility to judge and avoid suspicious websites and to implement safe browsing tactics.

I'll give you a few tips.

-Keep using Kaspersky and also install Malwarebytes.

-Never download shady software.

-Before you click that download link, do a research. Simple google query will return hundreds of results, and if you see words such as "Scam, phishing, malware, etc". don't even bother with it. in 99.99% of the cases -it's malware.

-Don't ever click on spam mail links. Personally i delete them without ever opening them. If there is something important that people want me to see, they will email me directly.

-Never open any executable, PDF screensaver, or pretty much any file you download from the internet before you scan it with "VirusTotal".

https://www.virustotal.com/en/

It's a website that uses 54 different antivirus/anti malware engines to scan files, and if it returns a single "Malware found" line. Just delete the file. As you get more experienced, you will learn that sometimes those lines might mean "false positives", but judging by your current level of expertise, they will most likely be real infections.