[Rehan]

Both Microsoft Edge and Google Chrome rely the Windows network proxy settings while Firefox has its own dedicated proxy settings. Check if you have a proxy enabled in Windows and make sure to disable proxy auto configuration.

A additional difference is that both Microsoft Edge and Google Chrome rely on the Windows certificate storage for SSL certificates and etc. while Firefox again has its own inbuild certificate storage. Not sure what to do about that but what if your Windows certificate storage is broken or something like that.

Do you have some kind of antivirus software that also has web plugins or similar? Turn off that kind of feature.

I am using Windows 7 Professional without any antivirus. I don't know what is problem. It is a fresh installed windows. What can i do? Do i try finding something in Windows Firewall and Security management? 
I want to use windows 10 but those automatic updates.

Both of these websites show up as "Secure" for me. I'm on mobile and using Chrome.

It's weird that Chrome and Edge flag a website as insecure when Firefox shows it's secure. Generally, I'd have recommended checking your system clock, but that isn't quite applicable in your case as you've another browser opposing.

I dunno, well, this is a very lame advice, but try flushing your DNS and check if it gets fixed or not. (After clearing cache completely)

Regards,

Soham i have tried clearing cache and re-installing windows and browser but still it is showing un-secure.