To be able to grant additional attempts, you will need to have the right permissions.
Management Console
User Management
Search for the relevant member of staff*
Select training records by locating the failed module from the list and clicking on it.
Scroll to the section titled 'Update attempt limit', change the user's attempt limit, and click the 'Update attempt limit' button.
* Additional attempts can not be granted in bulk to multiple users. You'll need to find each member of staff individually and give them more attempts per module.