STEP BY STEP:

If a Trainee has exceeded the number of permitted attempts at a course Assessment without passing the attempts will need to be reset.

Search for the Trainee and when you find them this click on View.  NOT EDIT.

Then click on Reset Attempts for the course.

When it first opens it will show you how many attempts they have already had.

Reset the number of attempts to 0 (zero) and click on Update.

Your trainee will now be able to attempt the assessment again.