By default the APA citation in Word 2007 doesn't quite match APA style (e.g. it doesn't convert a citation to et. al. when the citation has been made previously and there are many authors). Is there a work around the provides the desired behavior?
Try searching for "Word APA citation" or "BibWord APA". You can get an XSL file that you copy into the Word Bibliography\Styles subdirectory of your Word directory. I did that when I needed to use IEEE citation format, and it worked pretty well.
You may need to install the BibWord Extender to get it to say "et al.", not sure.
You may do it manually for the second and succeeding citations by editing the field.
Right click on the citation and select the "Edit Field" option.
For example, if the original citation was this:
(Johnson, Meyer, Lewis, Czerny, & Carroll, 2013)
The citation field would be something like this:
CITATION John13 \l 1033
If you edit it to this:
CITATION John13 \n \t \l 1033 \f "Johnson, et al.,"
(Johnson, et al., 2013)
If you need to do many citation, I personally use Endnote http://www.endnote.com/ as it is much better and more powerful than the Words built-in citation.
The cost of Endnote is pretty high but that's really depends on your usage. If you're heavily using it or makes good money from it then it should be worth it.
Change the Reference setting to CHICAGO and you will get the desired format you asked about. But the citation will provide et. al. if you have more than 3 authors.