Windows comes with Windows Defender by default, its
part of Windows Security.
Windows Defender used to be MSSE (Microsoft Security Essentials), which itself used to be Webroot AntiSpyware/antimalware. Microsoft bought Webroots App because it was so good and integrated well with windows, and rebranded it as Microsoft Security Essentials. At that time Windows had their own Defender, but after a while of developing MSSE they decided it was better than their own Defender .. So rebranded MSSE as Windows Defender (and got rid of their old defender), and included it with windows which it has been ever since, as part of the Windows Security suite of protection measures.
Other antimalware vendors didn't like that, because a) it was just as good as any of their paid for crap, and b) would be included for free in Windows, undermining the individual vendors profits once everyone realised how good Defender now is. But it was never given any fanfare (I think so that MS didn't get any anti-competetive lawsuits from people like Norton/Kaspersky etcetera). There was a bit of press crossfire at the time where other Antimalware vendors were trying to downplay Windows Defender, and a lot of fans of individual vendors saying it wasn't as good as Norton or whatever they believed in after years of good service.
Anytime I get a new laptop now, first thing I do is uninstall any sponsored antimalware (which are usually heavy on the system, and dont really get along well with windows itself because they have to be so intrusive), go into Security and turn on Windows Defender again (which the sponsored antimalware will have turned off when it was installed by the people selling the machine).
Beyond that I just stick to a few basic rules, never use pr0n or piracy/w4rez sites, always use a good DNS server like Quad9 to filter out all the bad crap on the internet and prevent me connecting with it in the first place, never click links in emails, and anything downloaded .. pass it through
Virustotal first (I mean the moment it lands on my machine Windows Defender gives it a scan, but its good to have a second opinion with Virustotals online scan using many different engines) before running it.
My thoughts about buying antimalware these days are we dont need it. Malware is so very advanced now if it gets on your machine it will run rings around anything you have installed which will not be able to detect it .. So why pay for antimalware when Defender (and your own good habits) will protect you from the same, if its going to get on your machine because of bad online habits the only way to get rid is to do a complete clean install of windows which wipes clean the hard drive in the process.
Also consider this .. Microsoft use their own Enterprise version of Windows Defender to protect their own internal infrastructure. Thats good enough for me
You should only have one Windows Security Icon in the system tray. If you want to do a virus scan just click the Security shield, and then go into Virus & Threat protection where you can access further options for Full scans etcetera. Click Scan Options, thats where you can choose a Full scan, but if you have doubts about your system choose the "Microsoft Defender Antivirus (offline scan)", this does a clean boot and executes Defenders best system scan before windows loads, then reboots to bring up windows again. The idea being anything installed at a low level to evade anything loaded by windows detecting it, is now not so well hidden by the system itself, and easier to eradicate by Defender. Screenshot ->
https://i.imgur.com/4AU4sQK.png
How you ended up with two icons idk
Windows also has another malware scanner which is maybe not widely known, but it does sneaky periodic quick scans as it conducts windows update installations, but never does an automatic full scan.
Click Start, and type in mrt .. When you see it listed choose run as administrator, screenshot ->
https://i.imgur.com/rYG9G7V.png . Then you can choose what type of scan it does when you go through its options, as another second opinion of your system to Windows Defender.