I'm answering myself and this might be of interest to someone else. I sent an email to the Thai Embassy in Paris to ask them the question and the answer is: "You can put either one" so both are correct, at least for this embassy. 👍
I will try to call the Embassy next week because I have your advice to write "Mont de Marsan" but somebody else on another groupe advice me to write only "France". So, I don't know, maybe the both are correct and maybe depending on which embassy... Wait and see
No, it's not mentioned on the RTE Paris, I have read this already I don't remember on which forum but looks like a wrong information if I read well your comment.
Thank you for the answer. So, let's say my visa is approved today, can I have my flight to Bangkok for example next October? I thought I had 30 days or 3 months before having to validate it at airport immigration. I'm not sure to be very clear. Thank you 🙂