Of you are only coming this year you could apply for a 6 month multi entry tourist visa or apply for the dtv

I stayed in thailand almost 2 years on 6 month tourist visas and such then recently switched to dtv. They will most likely ask you about your employment to make sure you aren't working illegally in thailand. I showed over a million baht in the bank and applied under soft power, but they asked for additional documents showing how I earned money outside of thailand and brought it in. I showed them deposits/withdrawals from my us bank I use to receive contracted work payments and that was enough. So long story short if you've been in thailand awhile be prepared to show how you have been and will continue to be able to support yourself without working illegally in thailand. As for taxes over 180 days you are responsible for filing taxes in thailand, but some countries have a tax treaty so everyone's situation is a little different. For usa we get credit for the taxes already paid on income in America and would be responsible to remit payment for anything owed beyond that based on thailands tax brackets.

You can only apply from outside of thailand, not while you are in the country.

If you more then meet the financial requirements just sign up for something and go soft power, make it easy on yourself.

My immigration officer was confused and had to ask the officer next to them, then they wrote in the end date for stamp and dtv

Don't forget your 180 days has a 90 day report to immigration. The stickers you see isn't the stamp it's a physical copy of the visa from someone doing on person not evisa, but they are the same.

The issue is they will accuse you of working illegally in thailand and denie the visa if you cant.

So most likely they will want evidence of where your money comes from since you've already been in thailand over 6 months

If you have been in thailand for awhile before applying some embassies are not only asking for the 500k statement but they want to know where the money came from. Need to show deposits or withdrawals from outside of thailand especially if using a thai bank account. Even under soft power they can ask about your employment and ability to support yourself without working in thailand so bring as much documentation as possible.

What did you bring in addition to your visa? Did you bring a certificate of residence or any other supporting documents? 3 banks isn't alot of tries either. Same bank different branch may yield better results. Dress well and bring as much supporting documents like residence certificate, house lease, thai license etc.