How can I correctly apply for a retirement visa extension in Thailand while on a Non-O visa?

Once you apply for your extension of stay and re-entry permit it will look like this ..

Your Non-O visa and your 90 day stamp should look like this

okay you're on a 90 day Non-O visa you got inside thailand at the immigration office. It should be stamped used and you should have a 90 day stamp in your passport too.

You can't get ANY Non-O-A visa <- those are gotten from a thai consulate in your country BEFORE you wash up here.

What you want is to apply for a yearly extension of stay based on being over 50 (retirement).

When you have 45 days or less (some offices want 30 or less) you go back out to your immigration office with your documentation and the bank letter, updated bank book showing the 800K baht has been in the account for 60 days prior to your application. They will stamp a yearly extension into your passport and AFTER you get that you can buy either a single or multiple re-entry permit

And if u Change this non o to retiried u just Need The Money on a bank Account in he Second year they May Be want to see if The Money is still there And nit Used or Taken.

If u leave thailand u Need an RE entry permit..or Buy a multiple for more then one time...

I think that you are confusing an extension of stay for the purpose of retirement with a non imm o-a multi entry visa. The non imm o-a is obtained in your home country via a Thai Embassy or Consulate. If you are currently in Thailand you would apply for an extension of stay based on retirement. That is good for one year. At the end of that year you will apply for a new extension of stay. If you wish to leave the country during that year you can purchase either a single reentry permit or a multi entry reentry permit.