Changing the location of "Description" field in Custom List?

Hello Forum,

In my Office 365 (SharePoint Online) I have a very simple Custom List which has a few columns/fields, and I added some description to add clarity to users. The problem is that the description's text gets added on the right-side underneath. Also,The company are not allowing using InfoPath nor any third-party solution. So, My only options are: SharePoint Designer & JavaScript.

Is there any way in SharePoint Designer or JavaScript to move the "Description" field under its column's text itself? Something like the screenshot below: 

Could you please guide me how to accomplish this?

I would sincerely appreciate any help in this, Please !

Thank you very much !