just walking into the bank they may have an issue. Get a certificate of residence, take it to the bank with your 800,000 Thai baht, your 90 visa, 2-3 copies of all the pages that have information on them, a W9 form copies to be safe, if they give you documents in Thai, ask for them to be in English, complete both Thai and English. If you don’t have a Thai friend it would be helpful. You need to have all the documents for the 90 day non-O and retirement visa completed with the same documents above copied. Treat each visa separately but you’re doing them together. Paying for each separately. And expect to only be making an appointment. But be ready to speak to somebody. Each branch may not have someone to open a foreigner account but they will know where to go or be able to create an appointment.
From the west coast of America, look at Send 2 Thai I used them and everything arrived as scheduled. They were even able to change the destination address before the ship arrived in Thailand.