These options are located in the Theme Options > Logo > Favicon tab.
You can upload an image file of any size as your favicon in 2 different devices; favicon for desktop and favicon for iOS and Android. (Fig. 1) What is a favicon?
Favicon options (Fig. 1)
Favicon – Illustrated as A. The main favicon for your website. Locate the ‘Favicon’ option and click the ‘Upload’ button to upload your favicon image file. Image must be 32px × 32px
Favicon For iOS and Android – Illustrated as B. This option is optional. For iOS and Android . Locate the ‘Favicon For iOS and Android ‘ option and click the ‘Upload’ button to upload your favicon image file. Image must be 152px × 152px