10-11-2020 10:47 AM
In theory you're supposed to be able to but usually it doesn't seem possible. And you won't be able to if it's the one with less than 12 hours to go.
If the reserve is not met when auction ends you can use Second Chance Offer to offer to the highest bidder at their highest bid price. The option will appear on the ended listing or via More Actions, far right of item on your unsold list.
Because the auction only has a couple of hours left to run. You can't make revisions when there are 12 hours or less to go.
it does not matter how log an auction has left to run, once there are bids you cannot add a reserve.