long-term retirement visa is a 90 day visa before the 90 days runs out,if you want to stay in Thailand, you must extend that visa 0they will allow you to extend the visa for one year. prior to applying for the extension You must have the money in the bank so on and so forth, but you always have the Visa. It’s the Ext that you have to do every year. 
I agree sending your transfer in USD is the best way, keep in mind the bank at least Bangkok Bank, where I send my money to my account, will always discount the current rate. The bank takes the difference in what they give you and what the current rate is, I guess is a service fee
why would you so casually respond to a remark with”so”. Does your country allow foreigners to come and stay as long as they want without a proper visa? I would guess no so why would you be so why would you think it’s OK when it comes to Thailand?
The US Embassy for some reason is unable to verify your US Social Security income, and give you an affidavit to that fact that’s why you have to have the money in the bank because I guess the embassy can’t figure it out.