BuddyPress.org

The avatars only works when I’m in BuddyPress pages.
I want to make it work around the site by adding the following code passing the user ID I found searching for:

<? php
$ Userid = bp_loggedin_user_id ();
echo bp_core_fetch_avatar (array ('item_id' => $ id user));
?>

But in which .phpeu add file this code?

Homepage:

Members area: