get the old bank to EFT to new bank account, show statements from both banks and bank books next visa application, as long as no break between the two banks you should be fine, but of course check with both sending and receiving banks that funds go and appear same day
well Mr mine is in some investment account that immigration has been happy to accept for the past two visa renewals, and yes you can add a d withdraw at will.
Make a will locally, there are rules on how long the actual 800k needs to be on the bank think it’s something like 3 months before 2 months after, if you can just put it in a term deposit and forget about it, interest at bkk bank is 1.6 % so you get a bit more than 10,000 after they deduct the tax, rubbish of course and if it’s locked up you can never fuck up.