Apply at the embassy in the country you are staying/living in. Apply for Non-O based on retirement. It's gives you 90 days initially. Enter. Open bank account asap. Bank the 800,000 tbt required for the 12 month extension. Extend every year for 12 months more.
Please explain why, if you already have a non-O, you'd change to the O-A that needs insurance linked to it and police background check. Just wondering.