The APA 6th settings allows you to display the first six authors (or editors) followed by the text preset to ( “, ...”) followed by the last author (or editor).
From the EditEndNote menu, select Output Styles, Open Style Manager.
From the Style Manager window, select APA 6th from the list of names, and then click the Edit button.
From the Style window, select Author Lists (or select Editor Lists if you wish to edit settings for editors) under the Bibliography.
Select the radio button that reads "If eight or more authors, list the first 6 authors, insert , ... and add the last author's name."
From the File menu, select Save As.
Give your updated settings a name (for example, "MY APA 6th Settings"), and then click Save.
Note: The default value is ", ..." You can, however, change this value - for example, you can set this value to "et al." or whatever style you choose.
Note: When this setting is selected, it overrides whatever settings are in the Author Separators and Editor Separators settings at the top of the panels.
The following example shows how your references will now display with the selected APA 6th setting.
Gilbert, D. G., McClernon, F. J., Rabinovich, N. E., Sugai, C., Plath, L. C., Asgaard, G.,... Botros, N. (2004). Effects of quitting smoking on EEG activation and attention last for more than 31 days and are more severe with stress, dependence, DRD2 A1 allele, and depressive traits. Nicotine and Tobacco Research, 6(2), 249-267. doi: 10.1080.1462220041000176305