Its safer because its open source...

Agree with you!

Android is secured but but the forked versions of Android are not so much I believe. Now why Android is secured - because there is regular monitoring of the security level of Android and whenever a loophole is identified, it is fixed immediately. Moreover there are monthly patches which takes care of security concerns.
Now being an open source, Android can be forked by any developer/OEM and they can add fuctionality to it as per their liking. Here comes the problem to be precise security concern. The level of scrutiny maintained by the AOSP, can not be maintained by the developer and as a result vulnerablities are created.

More about AOSP security can be found here

Clear Android is secure as much, as it is possible for Open-sourced OS - till someone won't find backdoor and use it, it is fully secured.

But all modified version like MIUI, EMUI, Flyme OS, Touch Wiz, etc... unfortunately not so much. I don't know why this happens, but developers of many companies during development makes many mistakes, and sometimes makes from really secure OS something, that is very unsecure and full of bugs.

Agree to the view! Depends on how you install apps, unknown sources, installing warez or cracked apps etc. And Flyme has a security app built in, along with Google's security patches, makes it more secure!

security is good :) Thanks