If this is a stupid question I apologise - if I leave Thailand and return within my first 90 days…

A. Do I still need to visit immigration on the date I should visit if I’d stayed for the full 90 days? Or

B. Does my 90 day clock then reset and I visit immigration 90 days from the date I return to Thailand?

Thanks for all the responses to my questions..I have yet another..my exit date when I entered is Nov 9....since it looks like I may have to leave and reenter for the 90 day..what is the latest I should wait to do it...I don't want to waste a month or so that I have already...am I correct in my thinking...and must I go back to the U.S. to apply or can I do Laos or Philippines? Thank you in advance.

My non immigrant o visa is at the 90 day leave country point. Is it possible to drive to the border at Cambodia or do I still need to fly out?