Memoir: How to trim set correctly?

Question

How do I set the trim correctly? In my case it was wrong on some pages.

\documentclass[a4paper,showtrims]{memoir}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[brazil]{babel}
\usepackage[paperwidth=18cm,paperheight=24cm]{geometry}
\usepackage{hyperref,lipsum}
\hypersetup{pdfpagelayout=TwoPageLeft}

% Trim options
\trimFrame  
\settrimmedsize{24cm}{18cm}{*} 
\settrims{0cm}{0cm}

\title{Memoir with Trim}
\author{R\'egis}
\date{\the\year}
%*******************************************************
\begin{document}

\begin{titlingpage}
  \maketitle
\end{titlingpage}

\tableofcontents

\chapter{Memoir with Trim}

\section{First section}

\lipsum

\chapter{Second Chapter}

\lipsum

\end{document}

Its is my result, wrong.

Answer 1

Is this what you want?

\documentclass[a4paper,showtrims]{memoir}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[brazil]{babel}
%\usepackage[paperheight=24cm,paperwidth=18cm]{geometry}
\usepackage{hyperref,lipsum}
\hypersetup{pdfpagelayout=TwoPageLeft}
\settypeblocksize{16.2cm}{*}{.75}

% Trim options
\trimFrame  
\settrimmedsize{24cm}{*}{.75}
\settrims{0cm}{0cm}


\title{Memoir with Trim}
\author{R\'egis}
\date{\the\year}
%*******************************************************
\begin{document}

\begin{titlingpage}
  \maketitle
\end{titlingpage}

\tableofcontents

\chapter{Memoir with Trim}

\section{First section}

\lipsum

\chapter{Second Chapter}

\lipsum

\end{document}