What is the process and requirements for extending a visa on arrival in Thailand for one week?

If you are on an arrival visa in Thailand and wish to extend it for an additional week, you can do so at your local immigration office. The extension costs 1900 baht and must be applied for in person, which means using an agent will not be beneficial. You may want to avoid visiting the immigration office on Mondays and Fridays due to higher foot traffic. Ensure to bring a passport-sized photo and a blue pen for the application. Note that there may be restrictions on extensions for certain nationalities, such as Indian citizens.