In Australia I had to get finger printed and pay for a police check.I then submitted to Thai Embassy and needed to get a Thai police check after sending fingerprints to them.
Apply from home country to through a Thai Embassy showing income through bank statements(65,000b/MTH) or money exceeding 400,000, no criminal record in Thailand and home country(police report and finger prints in my case).
Once here open Bank acc.,put in 400,000 keep for 3 mths, then maybe change visa.
The first time I got retirement it was from dealing with the Thai Embassy in Australia, showing my bank statements proving funds ,and 2 police checks Australia and Thailand and health Insurance for an OA( no other choice )