The Kit Kat update has killed all of my most useful apps, because it doesn't allow the user to write to the external SD card!
3rd Party file managers now don't work.
FTP clients, don't work (unless you download to the built in memory).
Text editors can't save to the SD card.
Scanning apps can't save to the SD card.
Podcast players can't save to the SD card.
AirDroid can't upload to the SD card.
...and so on.
You also can't delete anything from your SD card either.
This is a GOOGLE limitation on Kit Kat 4.4.2. T-mobile should not have released this update with this restriction. You don't seem to gain much, if anything, with this update (only a camera icon on your "lock screen"... and you only get that if you remove all security from your lock screen, like passwords, PIN codes, pattern, face detection etc).
If you use any apps that store to the SD card, I STRONGLY advise against installing this update.