Thanks for your response. I'll give it a try, and let you know the results.
And, I'm interested about BitDefender. I did go to several Mac sites, and it came fairly highly recommended.
Anti-malware software in general for macOS is unnecessary; add needless overhead on your system; and can cause problems of their own. macOS already has built-in malware protection called XProtect, although it isn't wholly foolproof and some of us, myself included, are of the opinion that it's fine to keep a second piece of malware software around to run only on demand as a second opinion, particularly as a troubleshooting option.
You have to be very wary of publications that "highly recommend" software. There are a lot of sites run by the developers of these same products touting them (the equivalent of infomercials) and a lot of tech sites have writers that quite frankly aren't all that "tech savvy". Many also rely on ad sponsorship by the very people whose products they "highly recommend". PC Magazine is one of the worst in this regard.
The reality is that there are no viruses for macOS, which are the most dangerous kind of malware that were most problematic for Windows in the past. This is a very specific kind of malware that can insert its code into other software, like a real-world virus does to cells. I believe these are potentially the only kind of malware that a real-time scanner may have any practical value to be used for, but since they don't exist in macOS, there's no need for it. Now, there are other types of malware out there for macOS, and while none of them can get on your system without your permission, mistakes do happen and people get tricked. That's why trojans are called what they are.
Adware is a growing problem in particular lately, so it's not imprudent to want to be careful, but going nuclear can cause its own problems. A quick perusal of these forums can validate that. Here, we previously advocated for Adware Medic, then Malwarebytes when they bought AM out and brought the developer on board. It's free to use on demand, but you can pay for a subscription if you want to schedule regular scans. I think it will even do live scans, but we've never advocated for that. But even that has started to fall out of favor as we're finding DetectX to be incredible. I know of two members here who found adware after being advised to try it recently and it found a piece of malware on my mother-in-law's iMac that Malwarebytes caught a couple years ago but apparently missed one component of. Other regulars know of other success stories... I'd been inactive here for some time and only learned about it a couple months ago when I started seeing it mentioned in posts here.
What's really great about DetectX is it can be set up to monitor changes to the locations that software is loaded from on startup (there are a few different places this is done from). If those locations are changed, DetectX will launch to alert you and offer to run a scan to see if there is any malware detected. The nice thing about this is it's not an active scanner constantly checking your system activity. The app itself isn't even running in the background. If I understand it correctly, macOS itself is screening for the changes based on a script that DetectX sets and launching DetectX if changes are made. This is also a very practical approach because any malware that gets installed in macOS also is going to need to get launched on startup. So rather than constantly checking EVERYTHING on your system, it's faster and more practical to just check the launch folders for changes, then scan the whole system if triggered. It's truly brilliant. And it's free for home users!