what do you mean, change the references. (or follow TMartin's advice!)
the way they are cited and listed, would be defined by an output style. I see JAMA (AMA 10th) is available in the output style download list (can get to the http://endnote.com/downloads/styles page from the Help/Endnote Output Styles and then put AMA in the first search box (Style or Journal Name). I usually don't put too much in it - or you miss matches.
Sometimes you need to look for other styles by the same publisher or in the same field.
Since I downloaded it, I attach it (I renamed it).
You would need to open the attached (it should open in Endnote) then "save as" (you can removed the word copy, automatically added by the "save as") and then to pick this output style in the word document's endnote tool ribbon (you may have to view all styles, or open style manager, to select the newly downloaded version).
(long time Endnote user)
Before you can add a citation, a works cited list, or a bibliography, you must add a source to your document. A works cited list is a list of sources, usually placed at the end of a document, that you referred to (or "cited") in the document. A works cited list is different from a bibliography, which is a list of sources that you consulted when you created the document. After you add sources, you can automatically generate a works cited list or a bibliography based on that source information. Each time that you create a new source, the source information is saved on your computer. You can use the Source Manager to find and reuse any source that you have created, even sources in other documents.
Citations are parenthetical references that are placed inline with the text. Citations are different from footnotes and endnotes, which are placed at the bottom of the page or end of the document. The source information stored in the Citations tool or Source Manager can be used to create citations, a works cited list, or a bibliography. However, you cannot use the information in the Citations tool or the Source Manager to create footnotes or endnotes.
For more information about templates for various styles, such as APA style, visit the Office for Mac templates web site.