I just joined so HI 5... eeee, HI 8

to every one here

And please, don't kill the Newbie.
It might be a silly question but where in Android installed in H8 Octa do I find option to allow install .apk from other sources than Play Store? Because all installs from usb drive failed so far. I don't see security settings in Android options. I even opened Developer options but no sign of Security settings.
Furthermore, after reading your Forum I will install 1.0.9 Futeko firmware instead of the one I have now HMD-1.0.9 2016-01-07.100054 from HI media site. Because, as I understand, it has been modified is some way? But please correct me if I'm wrong.

By the way, I got my H8 Octa beginning of December and I'm still struggling with sound issues; very loud buzzing when I start DTS or Dolby Digital movie which goes away after second or 2 as well as sound and video getting out of sync during the movie. Pause and Play helps for a while. Al this on Kodi 15.2 final version.
I tried different setting in Kodi and even upgraded it Kodi 16 from Play Store but now I lost any Pass-through capabilities. It is just buzzing, swooshing or hissing sound when I start to play a video. This sound is similar to sound you get when you test your speakers. It comes and goes. After switching off and on my Harman Kardon BDS880, while I play DTS movie sound fails down and comes back each 2 or 3 seconds.
I'm writing all this because I see a lot of people struggling with sound issues and maybe some one has similar configuration as mine. Sharing knowledge is power.

Anyway, I'm happy that Futeko forum offers some support. It's a pitty that it took me a while to get here.
Cheers