Hi,
IE11 should be there already.
Start>IE
Which security system?
Some are XP era (Spybot S&D) and should not be used with modern IE versions (>8) because they slow down the browser with ridiculously long restricted sites lists. It should be removed from windows 10 and a modern up-to-date av product used instead...
IE11 smart screen filter, which replaces the protection offered by Restricted sites lists.
Windows10 comes with Windows Defender pre-installed.
Regards.
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Rob^_^