Windows 10: Check Internet downloads to make sure they're free from viruses?

Hi,
Something Im curious about having recently read some posts about how people are using their PC to download and install programmes from the internet.
When a programmes/files are downloaded from the internet you always get the pop-up at the bottom of the screen asking if you want to Run or Save it.
I generally select to Run the programme if I'm going to install it because once its installed I'm not going to need it again. My understanding is that it is put into a temporary folder and then automatically deleted by Windows shortly after it has been Run and the programme has been installed. So to my way of thinking there's no point in saving it and then running it from the Downloads folder because Im not going to need it again. Ive read posts where some people say that when downloading from the internet they always use the Save option instead of the Run option. They select to Save the file to the Downloads folder. Then they run a virus scan on the file to check that is free from viruses/malware first before they Run it. Is that necessary?
I use the Edge browser and Windows Defender. I thought that Windows Defender real time protection automatically scans all downloads anyway to make sure they're safe and free from malware before you are able to Run the downloaded file.

:)

 

Internet Downloads

Thanks all for the useful suggestions, i certainly can understand the idea of refreshing downloads. I wish Firefox had that little button lol. Now i'll try and download Warrock (a great FREE game) with download manager though (annoyingly) firefox is now downloading without buggering up!
I just did a few spyware scans which though didn't stop the probs it probably did stop all thoses bloody programs from using the internet and slowing it down.

 

my mozilla browser is slow suggested I check windows for viruses

Your browser suggested you check for viruses? That was not your browser - it wouldn't do that.
You might want to download and run ADWCleaner.

 

Question on viruses and documents

Once the virus is removed just use a reputable antivirus program like AVG. I suggest AVG because it does check usb devices for viruses automatically once you stick the usb drive into the usb port.