T-Mobile has released a new software update N910TUBS2DQC1 for Galaxy Note 4 and N915TUBS2DQC1 for Note Edge smartphones in the US.
The latest update includes March security patch with fixes for vulnerabilities and exposures in the Android OS. Also, the firmware update includes device stability improvements, bug fixes, and performance improvements.
Software Update N910TUBS2DQC1 for Galaxy Note 4 and N915TUBS2DQC1 for Note Edge will gradually roll out to everyone. However, you can also check manually for updates, Go to Settings > About device > System update.