Two layers control whether customers can comment: board (tab) level for blanket policy, and per-post for one-off locks.
How to get there: Open the post → click the ⋯ more actions menu → Lock comments (or Disable comments).
Use this when one post is attracting noise (a heated debate, a closed/duplicate post, a security-sensitive item). Existing comments stay visible; new ones are blocked.
Admins can still comment internally even when comments are locked.
How to get there: Go to Settings → Boards → pick the board → open the tab → toggle Allow comments off.
Use this for boards where comments don't add value (e.g. a read-only roadmap view, a board that aggregates posts from elsewhere). Posts in that board allow voting but not commenting.
Toggle the same setting back on. Existing thread continues from where it left off.