Unwanted sign on each line of worksheet
<p>I don't know what the hotkey I accidentally clicked, but this <code>«¶</code> looking sign appeared on every line of code, and there are grey dots instead of spaces in the code.</p>

<p><img src="https://i.stack.imgur.com/pgJsP.jpg" alt="Click here to see the snapshot"></p>

<p>How can I get rid of those characters?</p>