Changing the encoding of text

Now, if we want to change text encoding in a file, we have to do it, word by word, if they are not in a paragraph or in continued artistic text. If we select multiple words together to change the encoding, it does not work. We need this to be fixed. Let's say, if I want to change the encoding of the text within a project, to be possible to change everything at once by selecting them all together, and not changing every single word or phrase, contained within..