Can the 400,000 Baht required for a Non-O visa extension be in a Thai savings account or does it need to be in a current account?

For the extension of stay based on marriage to a thai or raising half thai children the 400K baht banked money needs to be in a thai bank account in your name only where you can access the money.

That means it's either in a straight savings account OR in a fixed deposit account where the principal isn't frozen (meaning you can access the money any time even if you lose interest or get a penalty).