What are the financial requirements for my dad's Thai Non-O visa and how does it affect his bank account?

Hey guys! I have a question. I hope it doesn't come across as confusing to you as it is in my head: I placed my dad in VivoCare, a dementia care facility, here in Thailand at the beginning of February. He's an 82 yo Army vet with a full pension and disability. Once at VivoCare, they helped him open up a bank account with Bangkok bank with 800,000 baht that I provided. That month, I started sending 70,000 baht into the bank account via Wise from his US bank account every month, and will continue as long as he's there.

They keep telling me that after his visa (not LTV) gets approved tomorrow at immigration, I must continue to deposit 70,000 baht into his BBK account every month (which I knew), but that I can withdraw the 800,000 baht or spend it on his monthly rent at the facility. That makes me nervous: Can I draw the 800,000 down entirely? Or does at least 400,000 baht need to stay in that account? What about the thing where 800,000 (400,000?) needs to stay in the account 3 months after approval? Or is that a different visa route?

I'm trying to figure out what Visa he's getting. But more importantly, I don't want to draw the money too far down below the 400,000 baht or draw it too soon if it'll mess him up.

Please explain it to me because I keep asking them and they keep saying I can, but his immigration money isn't something I want to play with.