Have you checked the “Author Lists” setting* in the EndNote output style to confirm it is set to display “and others” for 3 or or more authors?
If the output style’s setting is correct did you try unformatting then reformatting the citations/bibliography?
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*Go to the EndNote toolbar, select EDIT, OUTPUT STYLES, EDIT name of the style you’re using. In the output style’s window locate “Citations” then click on “Author Lists”. In the right section of the window locate the “Abbreviated Authors” section and check if the abbreviation is set to “and others”. If not, change the setting and close the window which will save the changes as a new file so adjust both EndNote and MS Word to use the new output style file.
Can you describe how you change the output style? Is it in the word program itself? (which it needs to be) - and did you try select all and then unformating and reformating (from the word endnote ribbon (convert citations to unformated) or toolbar (unformat bibliography).