TM 30. I believe that you are supposed to register within 24 hours of relocation so when your family/you do the report, tell immigration you just moved.
to show immigration your balance on the day you apply for the visa and not the last time your account had any activity. At least that's what immigration told me.
Everyone keeps telling you to update your bank book and they are correct. What nobody mentioned is that you need some type of activity in your account the day you update it/go to immigration. Do a 100 Baht ATM withdrawal for example and then update your bank book.