Why don't Icomoon special characters work?

Question

css

When creating icon fonts on the Icomoon site, I noticed a special character that does not work. These special characters do not work in demo folders either.
They have documentation, but I don't really understand how it works. Can you please tell me how to use them? Here is the Making a Font documentation itself .

Answer 1

Scroll through the documentation to the excerpt from it I cited (the very bottom). There is a gif there that will answer your question.
Note: When using type tools in a desktop applications, do not enter characters that don't exist in your font. If you do so, the desktop application may switch your selected font to a different font. You should only be copy/pasting the characters that exist in your font.
The following gif demonstrates different methods of copying characters assigned to your glyphs.