Navigate to People, look up the user, look up the history record, select the history action icon to view details. Edit to Yes.
If you do not see the Authorize Retake option, as a SYSTEM ADMIN level user, when on this screen, click the EDIT button. Find the Authorize Retake column (Data Object Item), edit the record and give the field a display sequence in where you want the field to appear. Refresh your screen.
Please be sure to test after enabling this feature as different builds of AbilityLMS may not support a retake without additional configuration.
Authorizing a Retake ONLY applies to AbilityLMS (and LearnerWeb Enterprise) authored assessments. If the assessment is part of external technology, eg an AICC / SCORM / TInCan course or other assessment engine integration such as ISpring or ClassMarker, retake logic has to come from the external technology.