okay. I'm done trying to help. You refuse to listen. I and others have told you that it's not a requirement. I even told you how to verify that it's not a requirement. Yet you insist on hobbling yourself with a requirement that doesn't even exist. Good luck.
forget about DTV. Apply for the correct visa. Your sister got information about the non-OA retirement visa. That's not what you want. Apply for the non-O. Stop asking questions. Stop doing other things. Login to the e-visa system and start the application. Use the same options in the photo I uploaded. It will show you exactly what's required, and background check will not be one of the things it asks you to upload.
there's no such thing as applying in person. All Thai embassies use the e-visa system. You just need to select the 90 day non-O visa using the options in the screenshot I uploaded. There's no background check required for a non-O.
NEVER listen to anything an immigration officer tells you about embassies. And never listen to anything an embassy tells you about immigration. They're completely different government agencies that know nothing about each other.
Also you did not need to go back to the US. You could've just went to Laos and applied there. Or even bounced out and back in a few hours and then applied at immigration once your money seasoned long enough.
The requirement to apply for a visa is that you must be physically in the jurisdiction of the embassy in order to apply. That means you must be in the country of the embassy and not inside Thailand both to apply and until the visa is issued. The application specifically asks where you are physically at. Anything else would be based on fraud.
The legal requirement to enter Thailand as a tourist is to have proof of 20,000 baht or equivalent in another currency, proof that you'll be leaving Thailand in 60 days, and proof of where you'll be staying.