SX: \DeclareCaptionLabelFormat not working
https://tex.stackexchange.com/questions/520606/declarecaptionlabelformat-not-working
\documentclass{article}
\usepackage{caption}
\usepackage{float}
\floatstyle{plaintop}
\newfloat{graph}{tbph}{loh}
\floatname{graph}{Graph}
\DeclareCaptionLabelFormat{test}{#1 #2}
\captionsetup[graph]{labelformat=test}
\begin{document}
\begin{graph}[h]
\caption{Testing}
\end{graph}
\end{document}