You should be able to add field 31 to your references to make the DOI numbers appear in a Bibliography if you have the information filled in.
In Reference Manager go to Tools > Bibliography > Open Output style > select your style and click open > You would then click on the Bibliography Tab > On the left hand side select the Reference Type you want to change > In the middle of the screen place your cursor where you want the information to appear > Go to Insert Field button on the top left and go down the list to Field 31 then click OK > You can then go to File Save or Save as to make a new style based on the original.
You would then update your document or switch styles in your document.