Hello My Super Best Friends,

 

American citizen here. Going to Thailand without a visa. Can I upgrade to a Student Visa while in the country? Or what about a Non-B Visa? Can you upgrade at all while in the country, or will I be required to leave first?

It would be helpful to know what you are seeking to achieve.  The visas you mention are available (with the correct supporting documentation) from the Thai Embassy/Consulate in America.

If you wanted to attend a school it might be possible to change from a visa exempt entry to a non immigrant visa (category ED) but in most cases it cannot be done. One problem is that you must have 15 days remaining on your entry or the 30 day extension of it.

Same for the non-b category or worse since you have find a job and have work permit  application done first.

It would be best to apply for a single entry tourist visa before leaving the states.

If you were able to find a school and pay part of the tuition you could get the paperwork to apply for a non-ed visa before traveling.