@Ulli *******
as long as where ever you move TO you follow that immigration office's rules on how to change an address; some require both a TM30 and a TM28 (change of address form) some just the TM30.
So if you moved to Korat (and followed their process to change your address) yes you'd report there from then on and you'd get your next extension there.
Just so you know your situation is not the same as "I'm on vacation in another province and my 90 day report is due" ;)