@Gui***
I see you answered on another group that you ARE indeed an international student
SO what you'd do is you get documentation from your school showing when you graduate and then you go to immigrations before that extension you're on now expires and apply for the ED Plus extension .
They should give you a new year extension from the date your current one expires.
Now as far as what you do after that to switch it to a new visa type inside thailand, I doubt ANYONE knows seeing as this ED plus visa extension has been out only since July 15th.
Your first step is getting the extension you're on changed to the ED Plus extension. Because without doing that you're not switching to anything inside the country