How do I change header to application/json

I'm currently trying to pass a json data, and i want to change my ajax request header to application/json. This is waht i keep getting on my server Content-Type: application/x-www-form-urlencoded, application/json.

I used the ajax action of set request header, but it seems to be appending or so. How do i fix this, i only want the application/json, because django is still seeing it as a form

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