Set custom title colour in beamer title page

Question

I am trying to replicate the style of an Impress presentation that has a yellow on brown title in the title page. I have created a .sty file that opens with:

\mode<presentation>
\ProcessOptionsBeamer

% ---------------------------------
% color definitions
\usepackage{color}
\definecolor{new_yellow}{RGB}{251,190,94}

% ---------------------------------
% set colors of elements

% set the title color
\setbeamercolor{title}{fg=new_yellow}

In the .tex documents things are pretty normal:

\documentclass[aspectratio=169]{beamer}

\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage{courier}
\usepackage[T1]{fontenc}

% -----------
% Set new style

\usetheme{new}

% -- Section title pages
\AtBeginSection[]{
  \begin{frame}
  \vfill
  \centering
  \begin{block}{}
  \begin{beamercolorbox}[sep=8pt,center,shadow=true,rounded=true]{title}
    \usebeamerfont{title}\insertsectionhead\par%
  \end{beamercolorbox}
  \end{block}
  \vfill
  \end{frame}
}

%----------------
% Title and authors

\title{My presentation}

\subtitle{Coded with \LaTeX}

\author[Jane Smith]{Jane Smith}

\institute[The Institute]{The Institute}

\date{\today}

%====================================================================
\begin{document}

%----------------
% Title frame

% load backgound for title 
\setbeamertemplate{background}{ 
\includegraphics[width=\paperwidth,height=\paperheight]
{background_title.png}}

{ \setbeamertemplate{footline}{} % no footer on title
\begin{frame} 
\titlepage 
\end{frame} 
}

But the end result looks like this:

How can I apply the colour defined as new_yellow to the title page title?

Update: regarding the compiler, I am using pdflatex from TeX Live 2015:

$ pdflatex
This is pdfTeX, Version 3.14159265-2.6-1.40.16 (TeX Live 2015/Debian) (preloaded format=pdflatex)
 restricted \write18 enabled.
**

Answer 1

It turns out text colour must be explicitly applied when the title is inserted. This is something like: \textcolor{new_yellow}{\inserttitle}}. The same holds true for other elements in the title page, like sub-title or author names. Here is a full example of the title page in the .sty file:

% ---------------------------------
% title page

\defbeamertemplate*{title page}{customized}[1][]
{
  \vspace{0.05\paperheight}
  \usebeamerfont{title}\textbf{\textcolor{new_yellow}{\inserttitle}}
  \par
  \vspace{0.02\paperheight}
  \usebeamerfont{subtitle}\textcolor{new_yellow}{\insertsubtitle}
  \par
  \vspace{0.05\paperheight}
  \normalsize{\textcolor{new_yellow}{\insertauthor}}
  \par
  \tiny{\textcolor{new_yellow}{\insertdate}}
}