I used Springer template for my book, more concrete I used svmono.
Here is a MWE, that is the shortened version of my template file.
\documentclass[graybox,envcountsec,sectrefs,vecarrow,envcountresetsect]{svmono}
\usepackage[utf8]{inputenc}
\usepackage[vietnam]{babel}
\usepackage{savesym}
\usepackage{mathptmx}
\savesymbol{hbar}
\usepackage{helvet}
\usepackage{courier}
\usepackage{type1cm}
\usepackage{fouriernc}
\usepackage{esvect}
\let\remark\relax
\let\endremark\relax
\renewcommand{\thesection}{\arabic{section}.}
\renewcommand\definitionname{Định nghĩa}
\spnewtheorem*{remark}{Remark}{\itshape}{\rmfamily}
\renewcommand\remarkname{Chú ý}
\renewcommand\lemmaname{Bổ đề}
\begin{document}
\chapter{The direction of a segment}
\section{Some basics definition}
\begin{definition}
That is definition
\end{definition}
\begin{theorem}
This is theorem.
\end{theorem}
\begin{remark}
This is remark
\end{remark}
\begin{lemma}
this is lemma
\end{lemma}
\end{document}
I want to numbering the chapter like Chapter I, not chapter 1 as in this template did. I also want to numbering the theorem, definition, remark, lemma section-wise, i.e Theorem 2.1(the first theorem in section 2), the next enviroment(definition, lemma, ..) will be Defintion 2.2,..i.e use the same counter in a section for every enviroment(except the proof enviroment) ?
But how can I change the template to get that ? Please help me.