How do I extend my 30-day tourist visa in Thailand and what documentation is required?

Hello everyone, I need to extend my tourist visa of 30 days before getting non immigrant-o (in process).

My question are :

- do I have to give a proof of my exit of the country in the given extended time when I apply for extension ?

- where is the fastest bureau to get this done in bkk ?

- will I need proof of where I’m staying in bkk?

Thank you in advance 🙏🏻