Editing a reference creates a new bibliography item

Hi all, 

I’m currently having trouble editing my references correctly and I’m hoping someone can point out what I’m doing wrong. 

If I want to edit the fields of a reference I have previously cited, I use the standard route: Edit Citation(s) →  choose the referenceI want to edit → _Edit Reference → _which brings me to the website, where I can update the field I need change and → Save. Now instead of updating the information in my bibliorgaphy for all previous citations of this reference, it creates a new bibliography item altogether. I would need to go back and edit all the previous citations. 

Is there any way around this? My colleague uses the same steps and doesn’t have this issue. 

I’m hoping someone can guide me here, I would be very grateful! 
I’m currently using Endnote Basic, Style is J Amer Vet Med Assn and Microsoft word 2016. 

I’ve attached a screenshot of a test I did where I changed the year of a reference and it created a whole new item, leaving the first citation unchanged. 

Thanks for your help! 

Screenshot.JPG

That is because Endnote keeps the citation information in a “traveling library” associated with the paper, and if you change the year, it thinks it is a different citation and uses the info it saved in the traveling library rather than the one with the mismatched year in the  library.  Does Basic allow you to “convert to temporary citations”?  If so, when you “update citations and bibliography” Endnote should prompt you to replace those citations that don’t match anything in the library and you can select the altered one.