After 1 month of searching and investigating I have finally found out how to change wifi country code in android 5.
first of all you should have root access.
Look at the ScreenShots and do this levels step by step.
1. Install ES File Explorer.
Wifi only works for a couple of hour prefectly after a few hours if I turn of wifi wont it turn on again. I have used both 20150117 and 20150120 roms and in both of them this problem exist.
is there anyone else having this problem?