How detect viruses

GregdaMSP wrote:

...IS there a reliable free virus check app , if so what is/are they?

So... you want a second and add-on malware scanner? (More on platform security)

The add-ons have been entertaining though, as lately we've seen erroneous malware detections with those—false positives—and usually only when the built-in defenses then thwart efforts by the add-ons to corrupt macOS itself.

That's when the add-on apps aren't selling personally-identified online activities, of course.

For information on how to use Malwarebytes, you should contact the developer. However, what I do is download Malwarebytes once ever couple of years, run it and then delete it. Whenever I feel the need to run it, I download a fresh, up-to-date copy.

As there are no viruses that affect Macs, there is no reliable free virus detection software. There are a number of free programs but they are not reliable. There are also some ones that cost money. That doesn't make them any more reliable or necessary.

Avoiding malware on your computer is a matter of using the built-in protections, keeping your system software up-to-date (did you do the Rapid Security Response update that was released yesterday?) and using common sense and good judgment. See here:

Effective defenses against malware and ot… - Apple Community