check with Thai Embassy for full requirements you are responsible for knowing the laws and regulations for every country you visit. Just like in USA, ignorance does not help you. Go to the source for accurate info. Don't rely on Facebook.
If you plan to retire and not work, you will need the O Visa, or the OA visa. If you're over 50, and have the required amounts of money, they will work best for you. If you are planning on working, even part time, then the DTV Visa will work well. Compare all the visas and choose wisely. They each come with their own pros and cons.