diff --git a/lib/outputrenderers.php b/lib/outputrenderers.php
index 47d87283a06..1223ef64a8d 100644
--- a/lib/outputrenderers.php
+++ b/lib/outputrenderers.php
@@ -2496,12 +2496,13 @@ class core_renderer extends renderer_base {
         global $CFG, $DB;
 
         $user = $userpicture->user;
+        $canviewfullnames = has_capability('moodle/site:viewfullnames', context_system::instance());
 
         if ($userpicture->alttext) {
             if (!empty($user->imagealt)) {
                 $alt = $user->imagealt;
             } else {
-                $alt = get_string('pictureof', '', fullname($user));
+                $alt = get_string('pictureof', '', fullname($user, $canviewfullnames));
             }
         } else {
             $alt = '';
@@ -2533,7 +2534,7 @@ class core_renderer extends renderer_base {
 
         // Show fullname together with the picture when desired.
         if ($userpicture->includefullname) {
-            $output .= fullname($userpicture->user);
+            $output .= fullname($userpicture->user, $canviewfullnames);
         }
 
         // then wrap it in link if needed
diff --git a/lib/tablelib.php b/lib/tablelib.php
index 8235cbf1c81..a35a49a290e 100644
--- a/lib/tablelib.php
+++ b/lib/tablelib.php
@@ -1221,29 +1221,35 @@ class flexible_table {
             switch ($column) {
 
                 case 'fullname':
-                // Check the full name display for sortable fields.
-                $nameformat = $CFG->fullnamedisplay;
-                if ($nameformat == 'language') {
-                    $nameformat = get_string('fullnamedisplay');
-                }
-                $requirednames = order_in_string(get_all_user_name_fields(), $nameformat);
-
-                if (!empty($requirednames)) {
-                    if ($this->is_sortable($column)) {
-                        // Done this way for the possibility of more than two sortable full name display fields.
-                        $this->headers[$index] = '';
-                        foreach ($requirednames as $name) {
-                            $sortname = $this->sort_link(get_string($name),
-                                    $name, $primarysortcolumn === $name, $primarysortorder);
-                            $this->headers[$index] .= $sortname . ' / ';
-                        }
-                        $helpicon = '';
-                        if (isset($this->helpforheaders[$index])) {
-                            $helpicon = $OUTPUT->render($this->helpforheaders[$index]);
-                        }
-                        $this->headers[$index] = substr($this->headers[$index], 0, -3). $helpicon;
+                    // Check the full name display for sortable fields.
+                    if (has_capability('moodle/site:viewfullnames', context_system::instance())) {
+                        $nameformat = $CFG->alternativefullnameformat;
+                    } else {
+                        $nameformat = $CFG->fullnamedisplay;
+                    }
+
+                    if ($nameformat == 'language') {
+                        $nameformat = get_string('fullnamedisplay');
+                    }
+
+                    $requirednames = order_in_string(get_all_user_name_fields(), $nameformat);
+
+                    if (!empty($requirednames)) {
+                        if ($this->is_sortable($column)) {
+                            // Done this way for the possibility of more than two sortable full name display fields.
+                            $this->headers[$index] = '';
+                            foreach ($requirednames as $name) {
+                                $sortname = $this->sort_link(get_string($name),
+                                        $name, $primarysortcolumn === $name, $primarysortorder);
+                                $this->headers[$index] .= $sortname . ' / ';
+                            }
+                            $helpicon = '';
+                            if (isset($this->helpforheaders[$index])) {
+                                $helpicon = $OUTPUT->render($this->helpforheaders[$index]);
+                            }
+                            $this->headers[$index] = substr($this->headers[$index], 0, -3). $helpicon;
+                        }
                     }
-                }
                 break;
 
                 case 'userpic':
@@ -1251,14 +1257,14 @@ class flexible_table {
                 break;
 
                 default:
-                if ($this->is_sortable($column)) {
-                    $helpicon = '';
-                    if (isset($this->helpforheaders[$index])) {
-                        $helpicon = $OUTPUT->render($this->helpforheaders[$index]);
+                    if ($this->is_sortable($column)) {
+                        $helpicon = '';
+                        if (isset($this->helpforheaders[$index])) {
+                            $helpicon = $OUTPUT->render($this->helpforheaders[$index]);
+                        }
+                        $this->headers[$index] = $this->sort_link($this->headers[$index],
+                                $column, $primarysortcolumn == $column, $primarysortorder) . $helpicon;
                     }
-                    $this->headers[$index] = $this->sort_link($this->headers[$index],
-                            $column, $primarysortcolumn == $column, $primarysortorder) . $helpicon;
-                }
             }
 
             $attributes = array(
diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index c0bf984e078..fa122eabc75 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -3819,6 +3819,7 @@ function forum_print_discussion_header(&$post, $forum, $group = -1, $datestring
 
     $post->subject = format_string($post->subject,true);
 
+    $canviewfullnames = has_capability('moodle/site:viewfullnames', $modcontext);
     $timeddiscussion = !empty($CFG->forum_enabletimedposts) && ($post->timestart || $post->timeend);
     $timedoutsidewindow = '';
     if ($timeddiscussion && ($post->timestart > time() || ($post->timeend != 0 && $post->timeend < time()))) {
@@ -3856,7 +3857,7 @@ function forum_print_discussion_header(&$post, $forum, $group = -1, $datestring
     echo '</span>';
     // User name
     echo '<div class="media-body">';
-    $fullname = fullname($postuser, has_capability('moodle/site:viewfullnames', $modcontext));
+    $fullname = fullname($postuser, $canviewfullnames);
     echo '<a href="'.$CFG->wwwroot.'/user/view.php?id='.$post->userid.'&amp;course='.$forum->course.'">'.$fullname.'</a>';
     echo '</div>';
     echo '</div>';
@@ -3924,7 +3925,7 @@ function forum_print_discussion_header(&$post, $forum, $group = -1, $datestring
     // In QA forums we check that the user can view participants.
     if ($forum->type !== 'qanda' || $canviewparticipants) {
         echo '<a href="'.$CFG->wwwroot.'/user/view.php?id='.$post->usermodified.'&amp;course='.$forum->course.'">'.
-             fullname($usermodified).'</a><br />';
+             fullname($usermodified, $canviewfullnames).'</a><br />';
         $parenturl = (empty($post->lastpostid)) ? '' : '&amp;parent='.$post->lastpostid;
     }
 
diff --git a/user/classes/participants_table.php b/user/classes/participants_table.php
index 645a0cad600..8f999f51b47 100644
--- a/user/classes/participants_table.php
+++ b/user/classes/participants_table.php
@@ -366,7 +366,8 @@ class participants_table extends \table_sql {
         $enrolstatusoutput = '';
         $canreviewenrol = has_capability('moodle/course:enrolreview', $this->context);
         if ($canreviewenrol) {
-            $fullname = fullname($data);
+            $canviewfullnames = has_capability('moodle/site:viewfullnames', $this->context);
+            $fullname = fullname($data, $canviewfullnames);
             $coursename = format_string($this->course->fullname, true, array('context' => $this->context));
             require_once($CFG->dirroot . '/enrol/locallib.php');
             $manager = new \course_enrolment_manager($PAGE, $this->course);
diff --git a/user/lib.php b/user/lib.php
index 5e69105e3a6..44be4f4ee1e 100644
--- a/user/lib.php
+++ b/user/lib.php
@@ -335,7 +335,7 @@ function user_get_user_details($user, $course = null, array $userfields = array(
             $userdetails['lastname'] = $user->lastname;
         }
     }
-    $userdetails['fullname'] = fullname($user);
+    $userdetails['fullname'] = fullname($user, $canviewfullnames);
 
     if (in_array('customfields', $userfields)) {
         $categories = profile_get_user_fields_with_data_by_category($user->id);