If you would like to allow all users to view topics, whether they are logged in or not, you need to ensure that the ‘Permitted viewer roles’ field is empty.
In your dashboard, go to Discussion Board > Settings > User tab and deselect any items in the’Permitted viewer roles’ field. Click Save.
For more information, see the User tab settings article.
There might be several reasons for this. When viewing a topic, the comment fields aren’t visible so it’s not possible to respond to the topic.
- Your theme template doesn’t include comments. Try switching to a standard theme like Twenty Sixteen temporarily.
- You have comments enabled. Go to Settings > Discussion to enable.
- You have incorrect roles set for viewer / poster. Go to Discussion Board > Settings > User to ensure that users have the capability to view and post.