Let me start with mwe:
beamerthemeMwe.sty
%Mwe
\mode<presentation>
%%%%%%%%%%%%%%%%%%%%%
% COLOUR AND FONT
%%%%%%%%%%%%%%%%%%%%%
\definecolor{PurpleD-A100}{HTML}{B388FF}
\definecolor{dcol}{named}{PurpleD-A100}
\usecolortheme[named=dcol]{structure}
\setbeamercolor*{palette primary}{use=structure,fg=white,bg=dcol}
\setbeamercolor*{palette quaternary}{bg=dcol,fg=white}
\setbeamercolor{normal text}{fg=dcol}
mwe.tex
\documentclass[xcolor=dvipsnames]{beamer}
\usepackage{xcolor}
\definecolor{try}{HTML}{ff0000}
\definecolor{dcol}{named}{try}
\usetheme{Mwe}
\begin{document}
\begin{frame}{}
\begin{itemize}
\item Hello
\end{itemize}
\end{frame}
\end{document}
The problem is,the dcol defined in theme should be the default color, and I should be able to change the default color from my tex file.
But, here, I am getting the purple, even after defining a dcol in tex.
How I can make the dcol in tex to override the value given in sty?
\usetheme{Mwe}after\definecolor{dcol}{named}{try}, so the theme overrides your customization, not the other way around. – Matthew Leingang Oct 09 '20 at 19:10