Customize One Page CheckOut

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I have the GWT one page checkout code working in dev mode and everything is as expected according to the documentation.  My issue is I want to change the "My delivery details" page, but in dev mode it seems as though it is requiring a user name and password.  In my case I want it to go directly to the "My delivery details" page on startup, since I allow checkout without registration.  Is this possible and how?  I am new to GWT.  My real problem is I need to fix a bug in the GWT code to make United States the default country value.  I am on version 5.2, but do not want to upgrade to 5.5 yet.  Also, I am interested if this is possible for any other customization I may need to perform on the "My delivery details" page.  Thanks.