It doesn't look like adding/editing the description of a card causes any log to the activity history of a board. Is there a way to turn this on or to cause the logging to happen?
Editing the description of a card is not logged as a change in your activity/history, but editing the description of a board is.
Trello's (non-technical) instructions for recovering the description of a card that has been changed: http://help.trello.com/article/783-recovering-the-description-of-a-card-that-has-been-changed
Which, at the end-2019, basically says that there is currently no way to do this via web interface (apart from the already mentioned card export), but that it is possible via API:
- Get the card ID for the card. This is included in the URL of the card, after the /c/ - e.g.
hpAcP7ISis the card ID for https://trello.com/c/hpAcP7IS/814-multiple-log-in-credentials
- Go to https://trello.com/1/cards/CARD_ID/actions?filter=updateCard:desc, replacing
CARD_IDwith the card ID you noted above
- Look for
data.old.descfor the old descriptions
Note, one needs to have access to the card to get the change history.