according to APA6, the five level of headings are to be formatted as follows:
level 1
level 2
Flushed Left, bold, Title Case
level 3
indented left aligned, bold, lowercase ending with a full-stop.
level 4
indented left aligned, bold, italics, lowercase ending with a full-stop.
level 5
indented left aligned, italics, lowercase ending with a full-stop.
reference APA6 menu, p.62