You can replace text in references by opening the reference and then you can change the text.
Close the reference with the small (grey) cross and now the changes are saved.
There are two other possibilities in EndNote to change texts in references.
In this case you work in more references simultaneously.
First there is the possibility to replace text in all references or a selection of references.
This goes via Edit – Find and Replace. You will see the screen below.
Here you can indicate in which field you want to replace text (e.g. Author).
You can also choose to replace text in all fields (Any field).
Then you indicate which text must be replaced by another text.
In one action you can also change the contents of a field in all references (of a selection).
This can be done via Tools – Change/Move/Copy Fields.
Here you can add text at the beginning or at the end of a field, replace the complete content by something new or empty a field.
See the screen below.
It can be convenient to use this option, for instance after importing a number of references.
Then you can make a selection in which you want to add a certain feature (originated from…; or a subject that goes for the whole selection).
With the tab Move/Copy Fields in the screen above, you can copy the contents of a field to another field.
Hereby you can choose whether you want to maintain the original contents or not.