@Pete ******
Well I have never heard that and have been here 36 years. So I asked and got this answer: No, you cannot change a tourist visa to a Non-O visa at arrival in Thailand, but you can apply for a change of visa type while you are in Thailand on a tourist visa. To do this, you must apply at an immigration office in Thailand, have at least 15 days remaining on your current visa, and wait for the approval process there. The application must be made before your initial visa expires.