Type text into textarea on Jira defect page by using JQuery val() is not working

[Tam Vo]

I have a Jira site and I want to automatically submit a defect by populating title and description using JQuery, please see attachment below:

I added script $('div[spacing="comfortable"]').find('textarea').val('Modify bug 1');

On UI the text change from 'Bug 1' to 'Modify bug 1', but when I hover to the text area or click the confirm button, the value changed to previous text 'Bug 1'. I also try simulate human typing from article https://www.jqueryscript.net/text/jQuery-Plugin-To-Simulate-Human-Typing-typetype.html but no luck.

How I can resolve this case?