3. An apparatus, comprising: an input unit including a plurality of keys; and a controller configured to: when a word is selected and then a change key is entered, and a first character of the word is a capital letter, change the first character to a small letter, when the change key is entered in a state where the first character of the word is the small letter, compare a number of capital letters of the word to a number of small letters, and when the number of capital letters of the word is greater than the number of small letters, change all characters of the word to capital letters, and when the number of capital letters of the word is less than the number of small letters, change all characters of the word to the small letters.
3. An apparatus, comprising: an input unit including a plurality of keys; and a controller configured to: when a word is selected and then a change key is entered, and a first character of the word is a capital letter, change the first character to a small letter, when the change key is entered in a state where the first character of the word is the small letter, compare a number of capital letters of the word to a number of small letters, and when the number of capital letters of the word is greater than the number of small letters, change all characters of the word to capital letters, and when the number of capital letters of the word is less than the number of small letters, change all characters of the word to the small letters. 7. The apparatus of claim 3 , wherein the controller is further configured to: when partial characters including the first character of the word are selected and then the change key is entered, and the first character of the word is a capital letter, change remaining characters, except for the first character, among the partial characters to small letters, and when the change key is entered in a state where the first character among the partial characters is a capital letter, change the entire characters of the word to small letters.