By default, entrants can update their entries, both in progress and submitted, up until the end of your entry round. However, if you wish to prevent entrants from editing after submission, you can certainly do so.
Lock after submission
In the Manage workspace, go to Settings > Entries > General
Select the Entries locked after submission checkbox
Note: if the entry round is closed, you can extend it by changing the date in the Manage workspace at Settings > Entries > Rounds. Please note this adjustment will open the round for all entrants. To set a custom deadline for just one entry see our dedicated guide: Set a custom entry deadline.
Can a submitted entry be changed to 'In progress'?
Yes! Should the entrant need to update information within their entry for whatever reason, a program manager can return the entry to 'In progress' by following the steps outlined in our guide here: Revert an entry to in progress.