How to change text in ReplyKeyboardMarkup?

Question

Java

Guys, how to change the text of the buttons? Let's just say I have 4 buttons and one of them is something like a switch that changes the text.
Here is the button function:

public void sendBtn(SendMessage sendMessage){
        ReplyKeyboardMarkup replyKeyboardMarkup = new ReplyKeyboardMarkup();
        sendMessage.setReplyMarkup(replyKeyboardMarkup);
        replyKeyboardMarkup.setResizeKeyboard(true);
        replyKeyboardMarkup.setOneTimeKeyboard(false);
        replyKeyboardMarkup.setSelective(true);

        List<KeyboardRow> btn = new ArrayList<>();

        KeyboardRow keyboardRow = new KeyboardRow();
        keyboardRow.add(new KeyboardButton("1"));
        keyboardRow.add(new KeyboardButton("2"));
        keyboardRow.add(new KeyboardButton("3"));
        keyboardRow.add(new KeyboardButton("next"));

        btn.add(keyboardRow);
        replyKeyboardMarkup.setKeyboard(btn);
    }

And here is the until messages function (here the button function is called):

public void sendMsg(Message message, String text){
        SendMessage sendMessage = new SendMessage();
        sendMessage.enableMarkdown(true);
        sendMessage.setChatId(message.getChatId().toString());
        sendMessage.setText(text);
        try{
            sendBtn(sendMessage);
            execute(sendMessage);
        } catch (TelegramApiException e) {
            e.printStackTrace();
        }
    }