@Graham ******
TM30 has nothing to do with 90-day report. Your 90 day report date is governed either by your date of entry into Thailand, or 90 days from the previous 90-day report. The TM30 is registered each time you move address outside of the province in which you're residing. The TM30 app is excellent as it takes about 30 seconds to complete whilst you're sitting at home. It sure beats traipsing to the immigration office to do it. But of course, I always emphasise that it's each to their own, and whatever someone is most comfortable with