If you have a full TeXLive distribution, xelatex
should be installed already, and you should be able to choose Document→Settings...→Fonts→Use non-TeX fonts (via XeTeX/LuaTeX)
in LyX to have your document compile with xelatex
. If that doesn't work, you need to tell us more about how your TeX distribution was installed.
apa6
does not a provide a float-specific spacing as a document class option (see section 3.1 Class Options of the apa6
documentation, p 2). However, it loads the etoolbox
package by default which provides \AtBeginEnvironment{<env>}{<stuff>}
that hooks into and adds <stuff>
at \begin{<env>}
. So, you can use
\usepackage{setspace}% http://ctan.org/pkg/setspace
\AtBeginEnvironment{tabular}{\singlespacing}% Single spacing in tabular environment
Although it is not necessary to load use the setspace
interface for \singlespacing
in this case, it is just for convenience. If you're not allowed to use setspace
, you could also just use
\makeatletter
\AtBeginEnvironment{tabular}{%
\def\baselinestretch{1}\@currsize}%
\makeatother

Here is a minimal example using the former setspace
adjustment:
\documentclass[man,floatsintext]{apa6}% http://ctan.org/pkg/apa6
\shorttitle{Some title}% Dummy title
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{setspace}% http://ctan.org/pkg/setspace
% Already loaded by the apa6 documentclass...
% \usepackage{etoolbox}% http://ctan.org/pkg/etoolbox
\AtBeginEnvironment{tabular}{\singlespacing}% Single spacing in tabular environment
\begin{document}
\lipsum[1]
\begin{table}[ht]
\begin{tabular}{ccccccc}
\toprule
One & Two & Three & Four & Five & Six & Seven \\
\midrule
100 & 200 & 300 & 400 & 500 & 600 & 700 \\
100 & 200 & 300 & 400 & 500 & 600 & 700 \\
100 & 200 & 300 & 400 & 500 & 600 & 700 \\
100 & 200 & 300 & 400 & 500 & 600 & 700 \\
100 & 200 & 300 & 400 & 500 & 600 & 700 \\
\bottomrule
\end{tabular}
\caption{This is a table.}
\end{table}
\end{document}
lipsum
was merely used to create dummy text Lorem Ipsum style.
Best Answer
To set line spacing globally, go to Document ⇒ Settings ⇒ Text layout, and set line spacing to double here.