At most banks to get the bank book update machine to print the balance of the account (which you have to do on the day you apply for the extension) you need to have a transaction that day..
Most people just put 100baht into the account, then update the bank passbook and it will show the balance of the account on the day you apply :)
As far as if there are any changes, post on a Phuket group and ask,
This is the link to the Phuket Immigration volunteer website with the retirement requirements (but I don't know if it's still accurate or not)
You wanna read where it says "One Year Extension Requirements"
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