Korean Comments (Annotation) is hard to edit

I use the latest version of acrobat reader DC downloaded from the link: https://acrobat.adobe.com/kr/ko/acrobat/pdf-reader.html

When I try to edit the middle part of the contents after inputting the comments (annotations) in Korean, some of my further input is strangely passed to the last part. For example, the original annotation is 'abcd'. Then I move the cursor in the first part of the annotation. When I try to change the annotion (sticker note) '가나다 라마abcd', the modified annotation unintentionally change  to '가나abcd다 라마'. How can I solve the problem?