How to get there: Settings → Forms & fields → Form defaults, under Content & workflow.
These are the shared defaults for boards. Click Save changes after editing. Existing posts are not rewritten when you change form labels or instructions.
Manage the category library under Settings → Content organization → Categories. Configure structured post types and their fields in the adjacent Post types & fields tab.
Allow people to vote without logging in controls anonymous voting. Comment instructions supplies guidance above the comment field. These settings do not enable voting or commenting on a board where those interactions are disabled.
Open Settings → Boards, choose a board, then open Submission form (or Post defaults for changelog and knowledge base boards).
When the board inherits the portal defaults, a summary shows the active values. Enable Customize form text and access to give that board its own anonymous-posting permission and form text. Reset to portal defaults restores inheritance, so later changes to the portal defaults apply again.
Category selection has a separate Limit categories for this board override. Anonymous voting and comment instructions remain portal-wide.
Use Customize public view → Submit feedback on the board to show the submission button or a form beside the board. This controls placement; the form fields and defaults are configured as described above.