Web API Query Parameter

Hello Everyone,

I am having a little trouble in configuring the Web API's query parameter. By default 'username' is the available parameter but every time I remove it and try to add a new parameter it does stay as long as the Web API window is opened. But as soon as I save and close the window and then reopen the same Web API I find the newly added query parameter to be missing and also the default 'username' parameter is back. I am not sure if I am missing something here. 

Thanks for the help in advance!

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