How do I avoid strange characters like â or backslash in posts

Hey there,

When I am editing my pages with the TD Composer and save the changes, it sometimes happens that strange characters like â or backslashes appear.
For example: “let’s be realistic” or “that\\’s”

I’ve already tried lots of different things especially with the encoding options but they only worked temporary.
Is there any solution? Do I have to change something in the Newspaper theme data?

Thanks in advance and
best regards,
Max