diff --git a/appsettings/migrations/0021_setting_descriptions.py b/appsettings/migrations/0021_setting_descriptions.py
new file mode 100644
index 00000000..f44854d3
--- /dev/null
+++ b/appsettings/migrations/0021_setting_descriptions.py
@@ -0,0 +1,55 @@
+from django.db import migrations
+
+# what each setting does, shown under it on the Settings page
+DESCRIPTIONS = {
+    "INSTANCE_ARCH_DEFAULT_TYPE": "Architecture chosen first on the new VM pages",
+    "INSTANCE_MACHINE_DEFAULT_TYPE": "Machine type chosen first on the new VM pages",
+    "INSTANCE_FIRMWARE_DEFAULT_TYPE": "Firmware chosen first for a new x86_64 VM",
+    "INSTANCE_CPU_DEFAULT_MODE": "CPU mode chosen first for a new VM",
+    "INSTANCE_NIC_DEFAULT_TYPE": "Network card model chosen first for a new VM (default: libvirt's choice)",
+    "INSTANCE_VIDEO_DEFAULT_TYPE": "Video device chosen first for a new VM",
+    "INSTANCE_INPUT_DEFAULT_DEVICE": "Input device chosen first for a new VM (None: no input device)",
+    "INSTANCE_CDROM_ADD": "Bus of the CD-ROM a new VM gets (None: no CD-ROM)",
+    "INSTANCE_VOLUME_DEFAULT_BUS": "Bus of new disks",
+    "INSTANCE_VOLUME_DEFAULT_FORMAT": "Format of new disk images in directory pools",
+    "INSTANCE_VOLUME_DEFAULT_CACHE": "Cache mode of new disks",
+    "INSTANCE_VOLUME_DEFAULT_IO": "I/O mode of new disks (native needs cache none or directsync)",
+    "INSTANCE_VOLUME_DEFAULT_DISCARD": "Discard of new disks (unmap: the guest's TRIM frees space in the image)",
+    "INSTANCE_VOLUME_DEFAULT_DETECT_ZEROES": "Detect zeroes of new disks: how blocks of zeros the guest writes are stored",
+    "INSTANCE_VOLUME_DEFAULT_SCSI_CONTROLLER": "Controller model for disks on the SCSI bus",
+    "INSTANCE_VOLUME_DEFAULT_OWNER_UID": "Owner of new disk image files (0: root; qemu is often 107)",
+    "INSTANCE_VOLUME_DEFAULT_OWNER_GID": "Group of new disk image files (0: root; qemu is often 107)",
+    "CLONE_INSTANCE_AUTO_NAME": "Users who are not administrators get clone names made from the prefix",
+    "CLONE_INSTANCE_DEFAULT_PREFIX": "Prefix of the names made for clones: prefix1, prefix2, ...",
+    "CONSOLE_SCALE": "The console starts scaled to its window",
+    "CONSOLE_VIEW_ONLY": "The console starts view-only: no keyboard or mouse input",
+    "CONSOLE_RESIZE_SESSION": "The console starts asking the guest to fit its screen to the window",
+    "CONSOLE_CLIP_VIEWPORT": "The console starts clipped to its window, without scaling",
+    "SHOW_ACCESS_ROOT_PASSWORD": "Show Root Password on a VM's Access tab",
+    "SHOW_ACCESS_SSH_KEYS": "Show SSH Keys on a VM's Access tab",
+    "ALLOW_INSTANCE_MULTIPLE_OWNER": "A VM can be given to more than one user",
+    "QUOTA_DEBUG": "A quota refusal shows the numbers: what would be used and what is allowed",
+    "VIEW_INSTANCES_LIST_STYLE": "Instances page for administrators: VMs under their host, or one list",
+    "VIEW_INSTANCE_DETAIL_BOTTOM_BAR": "A VM's page shows a bar with its host's links at the bottom",
+    "VM_DRBD_STATUS": "The Instances page shows each VM's DRBD state",
+    "LOGS_PER_PAGE": "Rows per page on the Logs page",
+}
+
+
+def describe(apps, schema_editor):
+    """Descriptions that say what each setting does; they were tooltips
+    before, many only repeating the name. Not undone on the way back."""
+    AppSettings = apps.get_model("appsettings", "AppSettings")
+    for setting in AppSettings.objects.using(schema_editor.connection.alias).filter(key__in=DESCRIPTIONS):
+        setting.description = DESCRIPTIONS[setting.key]
+        setting.save()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("appsettings", "0020_fix_setting_choices"),
+    ]
+
+    operations = [
+        migrations.RunPython(describe, migrations.RunPython.noop),
+    ]
diff --git a/appsettings/tests/test_appsettings.py b/appsettings/tests/test_appsettings.py
index f15390b7..af8ca97f 100644
--- a/appsettings/tests/test_appsettings.py
+++ b/appsettings/tests/test_appsettings.py
@@ -99,7 +99,7 @@ class AppSettingsTestCase(TestCase):
         (field,) = page.xpath("//*[@name='LOGS_PER_PAGE']")
         self.assertEqual((field.get("type"), field.get("min"), field.get("max")), ("number", "1", "1000"))
         self.assertEqual(page.xpath(f"//label[@for='{field.get('id')}']/text()"), ["Logs per Page"])
-        self.assertEqual(page.xpath(f"//*[@id='{field.get('aria-describedby')}']/text()"), ["Pagination for logs"])
+        self.assertEqual(page.xpath(f"//*[@id='{field.get('aria-describedby')}']/text()"), ["Rows per page on the Logs page"])
         # a group is saved with its button, not on every change
         self.assertEqual(page.xpath("//*[@onchange]"), [])
 
diff --git a/appsettings/tests/test_migrations.py b/appsettings/tests/test_migrations.py
index ee44dc46..98cf4f5a 100644
--- a/appsettings/tests/test_migrations.py
+++ b/appsettings/tests/test_migrations.py
@@ -87,3 +87,15 @@ class ChoicesFixTestCase(TestCase):
             "INSTANCE_MACHINE_DEFAULT_TYPE": ("q35", "q35,pc,virt"),
             "INSTANCE_CDROM_ADD": ("sata", "None,ide,sata,scsi"),
         })
+
+
+descriptions = importlib.import_module("appsettings.migrations.0021_setting_descriptions")
+
+
+class DescriptionsTestCase(TestCase):
+    def test_every_setting_says_what_it_does_within_its_column(self):
+        limit = AppSettings._meta.get_field("description").max_length
+        for key, text in descriptions.DESCRIPTIONS.items():
+            with self.subTest(key=key):
+                self.assertLessEqual(len(text), limit)
+                self.assertEqual(AppSettings.objects.get(key=key).description, text)