I am Nepalese citizen (Nepalese passport bearer) in Australia on a Tourist Visa , I'm palling to visit Thailand on my way home to Nepal.
Can I apply for a Thai Visa from Australia?
No, only Australian residents can apply for a Thai visa in Australia.
Citizens of Nepal and 28 other countries need to use Form B. Part C of the form says,
::: IMPORTANT NOTE ::: An applicant must hold a valid Australian Permanent or Temporary Resident visa only. However, some certain categories of visass [sic] are not accepted, for example, Business Short Stay 456 Visa, Visitor Visa, ect [sic]
Citizens of countries other than the 29 Form-B countries use Form A; they are also required to be resident in Australia.