1. 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 small letter, change the first character to a capital letter, when the change key is entered in a state where the first character of the word is a capital 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 small letters.