This is the MacOS's Texshop disappearing apostrophe problem. 

```
% !TEX encoding = UTF-8 Unicode

```

is added to the document preamble.

Within the program:

Preferences=>Source is set to UTF8.

Preferences=>Misc has pTex support unchecked (this solved the problem for many, but not for me.

Under

Edit=>Substitutions none are checked. 

I have tried ' and ’ (prime and option-shift-right bracket) but the latter should always yield apostrophes but it doesn't. 

MWE:

```
% !TEX encoding = UTF-8 Unicode
\documentclass[10pt]{scrbook}
\usepackage[english]{babel}
\KOMAoptions{headings=small}
\usepackage{kpfonts}
\usepackage[paperwidth=6in,paperheight=9in]{geometry}
\setcounter{secnumdepth}{0}
\setcounter{tocdepth}{3}
\usepackage[normalem]{ulem}  %for strikeout text
\usepackage{mdwlist}
\usepackage{multicol}
\usepackage{makeidx}
\usepackage{idxlayout} %%to fix issues with index
\makeindex
\title{}
\author{}
\date{}

\begin{document}

    Apostrophes

Joe’s shoes are missing. 
So are Sam's.
The person's shoes.

\end{document}

```