@Samantha ********
All those above comments apply.
If you're Visa Exempt you get 30 days
If you're looking to extend your say ,you need to apply at the
Immigration office for the visa ,normally 30 days. Make sure your passport is up-to-date and you will need to fill another 3 forms you will be directed there.
A passport photo is needed to complete your application there's a kiosk nearby by
4 photos for 100 baht.
Now here's the CRUNCH LINE from my experience.I had booked paid hotel accommodation which they just casually looked at...the Immigration officer said you need to show a private persons details that can be contacted
Luckily i had my girlfriend's details which they accepted and stamped my form to proceed to get a visa
1900 baht cash only
the officer wasn't interested in flight departures
Always be polite and patient otherwise you could be in for a very bad day
Safe Travel