Then it will be not easy for you to apply for a longterm visa. Maybe it's possible to apply for an ED Visa or - in case you will find an employer - you may get a Non B visa in combination with a work permit for a specific kind of work. The most easy (and most expensive solution for you) would presumably be an Elite Visum.
Everything gets more easy if you were getting older than 50 years because then you can apply for a Non-O-Visa.
I would suggest that you have an intensive look at the website of the for you relevant Thai Embassy.
There you will find all necessary requirements for a possible longtime visa types that maybe will come into question for you! Good luck!