Yes you can definitely do that but it will require you to edit the theme files.

Edit the our_team_widget.php file located in the /inc/widgets/ folder.

On line 75 change the fa-instagram to fa-imdb

See here https://www.dropbox.com/s/973px6vwn93okcy/imdb-team.PNG?dl=0

You will see I circled it in red in the screenshot.

Let me know if you have any trouble.