Open a saved post's Info panel and the Activity section at the bottom shows its history: who created it, who edited which channels, title, tag and campaign changes, every schedule and reschedule, approvals, comments, and when it published or failed.
Edits are grouped, so a person's half hour of editing is one line ("changed X and LinkedIn content"), and an edit that was undone drops out. Hover a time to see exactly when it happened.