If you want to use latin1 (which is ISO 8859-1), then I have collected two solutions which are already mentioned in the comments.
The problem is, that in some cases* "A, "O, "U, "a, "o, "u, "s are
commands for special characters (instead of \"A, \"O or \ss{} for
example). So LaTeX cannot know what you mean in your example.
*Depending on the loaded packages, in this case, the babel package.
\documentclass{article}
\usepackage[ngerman]{babel}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{csquotes}
\begin{document}
\section*{They are all the same regarding the ß}
\begin{itemize}
\item "Test" s
\item " s
\item "s
\item But: "\ s % Thanks to comment of user Dũng Vũ
\end{itemize}
\section*{Solution 1: Use \texttt{babel}'s quotation marks}
% See also https://www.namsu.de/Extra/befehle/Anfuehrungszeichen.html
% https://de.wikibooks.org/wiki/LaTeX-W%C3%B6rterbuch:_Anf%C3%BChrungszeichen
% \glqq --> German Left Double Quote
% \grqq --> German Right Double Quote
% \glq --> German Left Single Quote
% \grq --> German Right Single Quote
\begin{itemize}
\item \glqq Test\grqq\ s (Don't forget the \textbackslash\ after the command)
\item \glq Test\grq\ s
\end{itemize}
\section*{Solution 2: Use the \texttt{csquote} package}
% For more information, have a look at the manual
% https://ctan.org/pkg/csquotes
\enquote{Test} s
\end{document}

Note: On the screenshot, you see on the bottom right that I use the correct encoding in the editor, in this case ISO-8859-1 which is latin1.
utf8instead oflatin1and it should work IMHO. Or it is angermanissue. – sztruks Dec 01 '18 at 18:01\glqq Term here\grqqif you want quotes in the output or resort to a package likecsquotes. – TeXnician Dec 01 '18 at 18:02utf8in both places. Sadly that didn't change anything – Dr_DragonKiller Dec 01 '18 at 18:05\usepackage[autostyle=true,german=quotes]{csquotes}and\enquote{test} sit works and I get the left one beeing down as well. Thanks – Dr_DragonKiller Dec 01 '18 at 18:11"is an error you should use left and right quotes – David Carlisle Dec 01 '18 at 18:11"Test" sto"Test"\ s. – Dec 01 '18 at 19:30