How To Control Where To Show User Avatars?
Go to the "Add-ons" page in the admin section (must be Jira admin to access this).
Look for "USER AVATAR" in the left panel, click "Display Configuration" under it.

Now you will see 3 check boxes (by default they are all marked).
You will see avatars if a check box marked, if you don't want to see avatars in a specific page, clear the check box, and save.
For example, if i want to see avatars only in "Issue View" without seeing avatars also in "Dashboards" and "Search Results" screens, it will look like that:
Free Version vs Paid Version