Notepad++ Case Chanfing Shortcuts
Ctrl + U        : lowercase
Ctrl + Alt + U  : Sentence case
Alt + U         : Proper Case
Ctrl + Shft + U : UPPERCASE

Blended Modes
Ctrl + Alt + Shft + U : Sentence case
                        Only first letter of each sentence is changed. Rest all letters are ignored.
Alt + Shft + U        : Proper Case 
                        Only first letter of each word is changed. Rest all letters are ignored.