You can control the time zone of the DateSignedTab on the Docusign Portal > Admin > Regional Settings. Please check the time zone you configured and update it accordingly in the "Time Zone" section. 
In the "Date Signed Field" section, check whether you select the "Account default." If it is selected with the "Recipient," the time zone will be shown as the recipient account's setting. More information about this setting is here: https://support.docusign.com/s/document-item?language=en_US&bundleId=pik1583277475390&topicId=wyk1583277329566.html&_LANG=enus

The selection is showing Kuala Lumpur, Singapore. But my time zone is Kuala Lumpur, Malaysia. 

Thanks for the clarification. I investigated and confirmed that there’s no option to show the Malaysian timezone (MYT) instead of “SGT.” This issue turned out to be a bug, so I filed the Jira case “ADMIN-19768” in Engineering. They will investigate further and fix this issue. Thanks again for raising this issue.

I would recommend opening a support case if you want to follow up on this issue. Here's the link to open the support case with Docusign: https://support.docusign.com/s/articles/How-Do-I-Open-a-Case-in-the-DocuSign-Support-Center?language=en_US