If you plan to move permanently or retire in Thailand I would recommend that you apply for a regular 90 days Non O retirement visa at your thai embassy at home first.
The formal requirement is that you’re passed 50 years for a non O retirement visa.
The financial requirement is a pension/income minimum equal to 65K thai baht a month OR funds equal to 800K thai baht. This may vary somewhat between the different embassies. You can use your bank at home to verify your income/funds.
When you come to Thailand you’ll need to open a bank account and put 800K thai baht within a month for to apply for your first year extension of stay, as your embassy doesn’t offer to give you a affidavit letter to confirm your income.
For your next year extension of stay you’ll have time to prove a monthly pension/income minimum 65K baht a month for twelve consecutive months and you can switch to the income method and don’t need any money saved in your bank any more. For the future yearly extension of stay you’ll just repeat this procedure. If you get a re-entry permit on your extension of stay you can more or less come and go as you wish in the future as long as you’re back in time to apply for your yearly extension of stay. The 90 days report is suspended while you’re out of Thailand.
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