I did mine before I came using the E Visa. Make sure you check which Thai Consulate you need to submit your application to. I believe there’s six in the US and each one has jurisdiction over specific states. I lived in Texas and the Washington DC Embassy is the one assigned for Texas.
When I got my visa, I applied at the Washington DC Embassy through the E Visa system. I applied for a 90 non O visa based on married to a Thai. I did not have to get a medical certificate or a police record clearance. When I got to Thailand and my visa was about to expire, I went and applied for the one year extension at which time of course you have to have the money in the bank I think it’s two months before you apply, but the entire process was very simple Very simple.  before you apply for your extension you need to go by the immigration office where you will apply for the extension and ask them for a list of documents. You will need to bring when you apply for the Ext.
Not always true Ronnie on my wife’s first attempt I thought it would be a slam dunk because she had already been to the United States and returned on her own when she came over on a K-1 visa and we got married. The second time I had a letter attached to the top of her folder from my congressman‘s office, asking the embassy to give her full consideration they never even opened up her folder. They just approved it she was in and out in about 10 minutes.
I think they have some kind of crazy quota system. It all depends on what time the month you come and how close they are to meeting their quota of giving out visas. But there’s no rhyme or reason for getting approved or disapproved.
I feel for you brother went through the same thing with my wife she got denied after she had already been to the United States on a fiancé visa with me when she decided she didn’t wanna live in the US so we came back to Thailand and she applied for the tourist visa denied on the first application Second time submitted the exact same paperwork and it was approved so go figure