Mine doesn't work. Oh, it works.   
What kind of apps you're interested in? Utility for office, home use or etc.

Did u turn on the security when u start setup ur phone?
It will ask ur confirmation everytime apps want to access certain things.
I didnt know at 1st then its too annoying and didnt know how to turn off so just restore factory setting and setup again

Yeap, you enabled the security on when you first setup your device. Two work arounds on this which is;

1) If you're being prompt the message again, you can select "remember my choice" and then click allow or deny.
2) Click on security app on your desktop > Permission > Manage app permissions > Apps on the tab > Click Whatsapp > Scroll down to contacts and select your option.

General setting -> battery -> battery indicator
However, percentage wont show during charging. Pretty stupid.