What are the new rules for the Non-O retirement visa regarding bank balance and documentation in Thailand?

today went to chiang mai immigration for non-o retirement extension. all went smooth within 1.5 hour. at the end the lady told my partner in Thai that we can only use the money after 3 months not further down than 400k. I would have expected that that new law starts at 1 march and not in February. however my stamp is ready till 5 march 2020. would it be for that reason that they look at the expiry date and not the actual visit date? also she did not mention how we have to proof that the money is there still 90 days later. no routine appointment for the check?