I just rooted my Note 3 and am I trying to access the hidden menu to activate band 4 LTE for AT&T. Each time I use a file editor, it says I have no permissions to save the file. I even used Super User being flashed, but that caused problems and my phone unrooted itself (strange, idk why.) How can I enable the hidden menu without permissions? I really need LTE on AT&T because the HSPA and HSPA+ speeds are atrocious. Any help will be appreciated.