How did Avast Browser instal without my knowledge ???

I’d like to try to discover exactly HOW … Avast Browser has installed itself on my PC - WITHOUT either my knowledge - OR CONSENT ??? I only discovered it by accident - when it made significant changes to my system and made ITSELF the default application for many things - all utterly without my knowledge or consent ?!
I want to know …
Is this browser safe ???
Is it GENUINE - or is it malware ???
HOW did it instal itself - totally without me knowing about it (given that it says it’s a 600Mb file size ?!)
CAN this browser be - SAFELY - uninstalled - WITHOUT the need to go trawling through all of the settings it changed manually ???
Any help that anyone can offer to me would be gratefully accepted, thank you.
Cheers.
:-[

It’s safe and it can easily be removed.
[url=https://forum.avast.com/Secure Browser Removal Tool https://download.avastbrowser.com/avast_secure_browser_uninstall.exe]Secure Browser Removal Tool https://download.avastbrowser.com/avast_secure_browser_uninstall.exe[/url]
If you don’t use a custom install when installing programs, it could have been installed silently that way.
Without knowing what other programs you use, I’d only be guessing, Avast?, Ccleaner?

It automatically installs with Avast Antivirus.

https://www.avast.com/compare-antivirus; https://support.avast.com/en-ww/article/44

Avast Secure Browser is a standalone installation. It does not come bundled with any current version of Avast. https://support.avast.com/en-us/article/Secure-Browser-FAQ

Also: https://www.avast.com/secure-browser

That could only have happened if you used the Avast SafeZone Browser which is no longer
used and was automatically converted to the Secure Browser.