you cannot "renew a visa". You can only get another 1-year extended stay permit. That Non-O visa you entered on, became invalid when you entered. You have been in Thailand on a stay permit since.
How will the bank know what your future visa status is after they have opened the account based on having a Non-Imm-O visa? The accounts being "closed" were opened on a touristic entries (including DTV in some cases), or the SIM-card number registrations didn't match the person holding the account. Everything else is irrelevant after the OP has opened a bank account on the correct visa
FIRST: you didn't renew your visa, as you have no visa any more. You only got a new one-year extended stay permit. SECOND: the OP will open the bank account on the correct visa. What he will be doing in the future, is irrelevant to the bank account
you can apply for the 90-days Non-Imm-O Retirement Visa through the E-Visa online system of the Royal Thai Embassy London. Once entered Thailand, get a bank account opened and transfer a minimum of 800,000 THB onto it. And as soon as the money has sat in the account for 2 months, you can apply for the 1-year Extension of the Stay Permit based on Retirement
the Non-O/A visa is the "Longstay" visa. The "Retirement" visa is the Non-Imm-O visa (without "A"). I do not recommend the O/A visa for people who wish to retire in Thailand because it includes a mandatory Thai private tgia-listed health insurance after the second year. If you start out of a Non-Imm-O visa, you maintain a freedom of choice regarding your health insurance
will enter Thailand on a 90-days Non-Imm-O visa. He will visit an agent and get a bank account opened. Legally and rightfully. Before the 90 days are up, he will exit Thailand. And whatever and whenever he returns to Thailand, it definitely won't affect his Thai bank account. That's gonna be the fact, and none of your speculations. . . you and the thousands of others have, in the recent 24 months, opened your Thai bank accounts on the wrong visa, and that's why you all are facing the consequences. If you had the correct visa when you opened your account, everything would be fine
there is an option where parents of children who are attending school in Thailand, can "piggyback" as "supporting family" on the Non-Imm-ED visa and the yearly extensions of the stay permit of their children until they are 18 years old. This is an option you must discuss with both the embassy in Berlin, and the Immigration office in Bangkok