Some people Tend to use UpperCase and lowercase cREATIVELY. Others like to emphasize Words they consider Important. A few like to SHOUT. If it only happens once in a while to a few words, it's no big deal to change the text manually to the case you want. But if you want to change the case of a long string of text, Word comes to the rescue with its Change Case command.
To alter the case format of text, you can position your cursor within a single word or select a section of text, and then choose the Format, Change Case menu command.
A dialog box appears that allows you to change the case of the selected text to UPPERCASE, lowercase, Title Case, sentence case, or tOGGLE cASE.
When you have a document loaded with case errors and you don't want to futz with menus and dialog boxes, you can select your text and press Shift-F3 until you get the case you want. This key combination toggles among upper, lower, and title case.