Converting regular quotes to smart quotes aka: curly quotes in Article Manager requires a couple of steps to enable it on your text in the article body. 

Step 1: Write your text and put regular quotes around the text where you would like to insert smart quotes. 

Step 2: Highlight your text and regular quotes

Step 3: Open the additional text formatting tools using the three dots next to the text formatting group, select the smart quotes icon while your text is highlighted, you will see the quotes change to smart quotes. 

Step 4: Remember to save and clear cache