I don't want to get my PC infected again so I need to try and avoid it. But I don't know where it is.

There are several anti-virus and anti-spyware programs on the market. Do you have a specific one in mind?

Which one are you looking for ?

This one? Malwarebytes' Anti-Malware: Malwarebytes

No it's named "Security Tool"

"Security Tool" aka "Security Tool virus"

Its not necessary to add a comment to each response. Use the Answer options at the bottom to just respond to the thread.

I'm not clear are you looking for a tool to specifically clean out a particular virus?

No it looks like a antivirus but it's actually a virus

As this is a drive by infection it's very difficult to know exactly where you got it from.

It's quite a popular infection that goes by different names. It's been keeping my little side business of tech support a little busy.

Here's a good article related to it: LizaMoon infection: a blow-by-blow account