A rule for some of the bibliographic styles (i.e. APA 6th) is that first name/initials must be inserted when you have multiple citations of authors with same last name in your article/document.
If you see that some of your citations got first names/initials, then this is probably because of this rule.
But most times you know that the author is the same, and first name/initials should not be written. Why then does EndNote insist on inserting the first name/initials?
Solution
This is because you have probably written the first name/initials differently in your EndNote library.
- "Smith, John"
- "Smith, J."
- "Smith, J"
- "Smith, John "
These four authors are all with different first names/initials, and will by identified as four different authors by EndNote. Please note the extra space after John in the last one.
Open your EndNote library. Search for the last name of your "problem" author/citation, and check each and everyone of these references. Make sure they are written exactly the same.
Fastest solution is probably just to copy from first reference, and overwrite-paste the author name into all the other references.
When done, go back to your Word document, and click "Update citations and bibliography", and hopefully the first names/initials will disapear.