Authors and multiple authors are handled in the same way for all references.
(There are some exceptions which are not shown here).
Refer to the 7th edition, Concise Guide to APA Style: the official APA style guide for students - Inside cover or chapter 8, pg. 181, 8.10
Please review Chapter 8 for additional information on in-text citation
Last name, First. Middle Initial(s). (there won't always be a middle initial).
Smith, J.C. (2012).
In-text: (ex1) (Smith, 2012); (ex2) Smith (2012) discovered...; (ex3) In 2012, Smith discussed in her study of...
Smith, J.C. & Jones, A.T. (2012).
In-text: (ex1) (Smith & Jones, 2012); (ex2) Smith and Jones (2012) deduced that...; (ex3) In 2012, Smith and Jones produced a study...
Smith, J.C., Jones, A.T., Parker, A., Trooper, B., Johnson, K.J., Kalun, P., & Daigle, R. (2012).
In-text: (ex1) (Smith et al., 2012); (ex2) Smith et al. (2012) discovered...
Smith, J.C., Jones, A.T., Parker, A., Trooper, B., Johnson, K.J., Kalun, P., Jones, A.T., Parker, A., Trooper, B., Johnson, K.J., Kalun, P, Jones, A.T., Parker, A., Trooper, B., Johnson, K.J., Kalun, P, Jones, A.T., Parker, A., Trooper, B., Johnson, K.J., Kalun, P . . .Miller, S.C. (2012)
In-text: (ex1) (Smith et al., 2012); (ex2) Smith et al. (2012) discovered...