Change of Status
While in the United States, you may be able to request that U.S. Citizenship and Immigration Services (USCIS) change your nonimmigrant status to another nonimmigrant category. See Change My Nonimmigrant Status on the USCIS website to learn more.
Requesting a change of status from USCIS while you are in the United States and before your authorized stay expires does not require that you apply for a new visa. However, if you cannot remain in the United States while USCIS processes your change of status request, you must apply for a visa at a U.S. Embassy or Consulate.
Visa Waiver Program
Persons admitted under the Visa Waiver Program are not permitted to change status in the United States. See Change My Nonimmigrant Status on the U.S. Citizenship and Immigration Services (USCIS) website.