How to specify content type in security definition

I am trying to set up swagger UI and the authentication portion. I am using oauth2 and the password flow for the security definition. When I send a request I see that the content type is application/x-www-form-urlencoded. Is there a way to configure this? I need it to be application/json. Would I be able to do this in the spec or through the swagger ui react component that I'm using?