is there any chance to get premission to modify files on SDcard???
i have got excel files and i can;t save it after modyfing - "premission deneid" ....
You need to root your phone.
The best guide is this: http://xdaforums.com/showthread.php?t=2642081
Then, you can backup your DRM keys, and unlock your bootloadear (the backup is for relocking it, and "restore" your warranty )
I didn´t want to unlock the bootloader... so only rooted the phone. Then, installed SDFix, Xposed, and System app uninstaller... and then this phone became even better