UI improvement on correct answer should be locked instead of allowing learner to type in text box

Currently for online quiz assessment type, if build attempt is ticked, it doesn't allow learner to change previous attempt, but it allow learner to type/replace the answer. learner then click "next" thinking that it save the answer, but in reality it doesnt.

so the build attempt as technical function does work, it prevent end user to overwrite answer that is already marked correct but the text box still allow the learner to type something on top will be confusing. it should just grey out or doesnt allow learner to overwrite anything and read only.