1. Click Admin.
2. Navigate to Channels > Channels via the left-hand navigation bar.
3. Locate the channel.
4. Click the pencil icon on the far right of the channel.
5. Scroll down to Advanced Settings.
6. Locate the Attachments security level menu.
7. Specify a more permissive value, either Relaxed or Permissive, as needed.
8. Click Save at the bottom right.