Updating bibliography

When I notice that a reference was somehow incorrectly entred by the library (source) and I have already cited that reference in my document I have no luck updating it. I manually alter the reference in my endnote library and then choose update bibliography. I end up with two references to the same journal article and if I choose the update one then I end up with two entries in my reference list as well.

For now, I am checking references before I cite them and resorting to changing the plain text document after finishing the report. I hope to resolve this problem before I write longer reports, and require same references in many papers…any help would be appreciated. 

Thanks for pointing out the edit function. I had been doing everything via the library rather than editing. I will give your solution a try. TIA

hello, I have a problem can you help me, please. I have formatted my references using Endnote X9 and when I finished formatting and at the end, I added a  new citation in the text and then my all formatting becomes zero and it returned to 0 where I stared. How can we keep formatting safe if we add the new reference after completing formatting?