By default, the author/co-authors can't edit their ideas post submission.
As a sysadmin/subsystem admin, there are 2 approaches to solve this:
- Allowing them to edit only the submission fields they inserted as long as the idea is in specific state(s)
See this article - Defining them as state owners.
This will give them stronger permissions a explained in this article
The steps to do it are the following:- Go to the main setting "Settings" option and then choose "Workflow".
- For the state "Discussion" choose "Owner" icon from the list of icons

- Select the Author/Co-asuthors to be the state owners of the state

Make sure you don't grant mistakenly state transition permission to the Author/Co-Author role.