I have a problem

[bug]

How i install android 4.1.2 because i installed android 4.2.2.and he have bug

[Cot88]

You have to root your phone and flash another firmware

Here you can find a guide

http://talk.sonymobile.com/t5/Android-development/GUIDE-How-to-Root-Xperia-Smartphones/td-p/287857

Remember that this operation will void your warranty and could brik the phone