Every asset in the Library has three built-in date fields Due date, Publish date, and Expiration date grouped into their own Dates section on the asset's Info panel. That's where you set or change any of them.
Steps
Open the asset. From the Library, click into any file to open it in the asset viewer. The Info tile on the right-hand rail is selected by default.
Find the Dates section. Scroll past the compliance score, the Approval section and the Summary to the Dates section, just below the Summary.
Reveal the field if it's hidden. The panel only lists fields that already have a value. Empty ones collapse. Click Show N empty fields (for example, Show 2 empty fields) if Due date, Publish date, or Expiration isn't showing.
Edit in place. Double-click the date value (or click its pencil icon). That row turns into a date picker right where it sits.
Pick a date and click away. There's no Save button: the section header reads Saves when you click away, and the moment you click outside the field the date is committed. If a save fails, the row shows Not saved with a Retry link. There's also no undo, so double-check the value before clicking away.
Where these dates matter
Social posts work a bit differently. For a Reach post, the Publish date is still edited from the same panel, and changing it updates the post's schedule.
These dates aren't cosmetic. Dates you set here show up across Warrant, in search, list views, exports and compliance scans, not just inside the sidebar.
If a date field is missing or read-only
Hidden by an admin. Built-in panel fields, including Due Date, Publish Date and Expiration Date, can be turned off per company under Settings → Fields & option lists → File Details Fields. Turn off all three and the Dates section disappears. Hidden fields keep any value they already had, they just stop showing.
Read-only, not hidden. If your company's workspace is in read-only mode, you'll see the value but won't get an editor on double-click. Restricting who can edit a field (admins only, or admins and the asset's creator) applies to custom fields, not to these three built-in dates.