Change Case

(Home Tab, Font Group, drop-down) - SS
(Format > Change Case)

Ctrl + Shift + A to alternat between all uppercase and all lowercase.
Shift + F3 to cycle through all lowercase, initial caps and all upper case.

Sentence Case

Capitalizes the first letter of the first word in the selected sentences.

Lowercase

Changes all selected text to lowercase letters.

Uppercase

Changes all selected text to capital letters.

Title case

Capitalizes the first letter of each word in the selection.

Toggle case

Changes all uppercase letters to lowercase in the selection and vice versa.