How can an American extend a Visa Exempt stay in Thailand?

What country in America, then it can be narrowed down for the answer.

if you are on visa exempt, you go into your local immigration office with: a printout of proof you are staying at your current hotel, a passport photo, a copy of your passport main page and the one with your Thailand stamp, your actual passport, a pen to fill out the official extension form since the ones in the office probably won't work, 1900 baht, some patience... worked fine for me, my wife, and 5 year old son last week in Chiang Rai. Chiang Rai immigration is at the mall, so good to get lunch, and has an indoor playground for kids, so all good!

He has a visa in his passport . It is a visa except visa. Oh English ….

VOA is 15 days. You buy it at airport when you enter. But only certain countries do that. You've probably entered without a visa, on the 60 days exempt. Can go to immigration and extend it for 30 days.

Firstly clarify if you have a 60 day visa on arrival or a 60 day visa exempt stamp in your passport.

go to the nearest immigration (it square, near lak si train station, red line) if you are in bkk, with tm30 and passport, 1900b, bring a pen, photocopy your passport at the same place, there is 3 copy shops at the same floor.