Using \renewcommand to define sections

Question

I'm trying to define my sections for my research paper using APA guidelines :

Section : Centered, Boldface, Uppercase and Lowercase Headings

Subsection : Left-aligned, Boldface, Uppercase and Lowercase Heading

Subsubsection : Indented, boldface, lowercase heading with a period. Begin body text after the period.

To do so, I am using the following commands :

\makeatletter
\renewcommand*{\addperi}[1]{#1.~}
\renewcommand{\section}{\@startsection {section}{1}{24pt}%
{\parskip}{-\parskip}%
{\centering\normalfont\normalsize\bfseries\addperi}}

\renewcommand{\subsection}{\@startsection{subsection}{2}{24pt}%
{\parskip}{-\parskip}%
{\normalfont\normalsize\bfseries\addperi}}

\renewcommand{\subsubsection}{\@startsection{subsubsection}{3}{24pt}%
{\parskip}%
{-\parskip}%
{\normalfont\normalsize\bfseries\addperi}}
\makeatother

However, my sections, subsections and subsubsections all look the same : the sections are not centered but indented and are followed by a period; the subsections aren't left-aligned but indented, and followed by a period, and my subsubsections look just right. Basically all of my sections look like subsubsections.

The document class is : \documentclass[doc,apacite]{apa6}

Answer 1

The default settings from apa6.cls give you most of your requirements; the only thing that you might need to adjust is the spacing after the sections and subsections; those spaces are controlled by lengths (skips) \e@level@one@skip (for sections) and \e@level@two@skip (for subsections). The default values are

\e@level@one@skip=0.2\baselineskip \@plus .2ex
\e@level@two@skip=0.2\baselineskip \@plus 0.2ex

so you need to adjust those according to your requirements. For example:

\documentclass{apa6}
\usepackage{lipsum}

\makeatletter
\e@level@one@skip=1\baselineskip \@plus .2ex
\e@level@two@skip=1\baselineskip \@plus 0.2ex
\makeatother

\begin{document}

\section{A Test Section}
\lipsum[4]
\subsection{A Test Subsection}
\lipsum[4]
\subsubsection{A test subsubsection}
\lipsum[4]

\end{document}

Will give you