How to convert a selection to lowercase or uppercase in Sublime Text

For Windows:

• Ctrl+K,Ctrl+U for UPPERCASE.
• Ctrl+K,Ctrl+L for lowercase.

Method 1 (Two keys pressed at a time)

1. Press Ctrl and hold.
2. Now press K, release K while holding Ctrl. (Do not release the Ctrl key)
3. Immediately, press U (for uppercase) OR L (for lowercase) with Ctrl still being pressed, then release all pressed keys.

Method 2 (3 keys pressed at a time)

1. Press Ctrl and hold.
2. Now press K.
3. Without releasing Ctrl and K, immediately press U (for uppercase) OR L (for lowercase) and release all pressed keys.

Please note: If you press and hold Ctrl+K for more than two seconds it will start deleting text so try to be quick with it.

I use the above shortcuts, and they work on my Windows system.

From the Sublime Text docs for Windows/Linux:

Keypress            Command
Ctrl + K, Ctrl + U  Transform to Uppercase
Ctrl + K, Ctrl + L  Transform to Lowercase

and for Mac:

Keypress    Command
cmd + KU    Transform to Uppercase
cmd + KL    Transform to Lowercase

Also note that Ctrl + Shift + p in Windows (⌘ + Shift + p in a Mac) brings up the Command Palette where you can search for these and other commands. It looks like this: