Featured Content and Featured slider no editting

Hi everyone, Could you please someone help me with the featured content and slider problem. I could not add new featured content to my web site. In the section appearance > customize > featured content, new featured content adding options are not seen. Still, I have previously added featured contents on my homepage (in News&Events section), but it is not possible to add a new one. The same problem also exists in the featured slider section as well. Nothing is seen when I enter the appearance > customize > featured slider :( Thank you all in advance.