In the Module Settings of the Audits module, you'll have a switch 'User Selection Criteria':
When the switch is turned Off, only Users from the Group(s) you have selected in the Groups field will be available to be assigned in roles when creating/editing a Qualification/Audit.
Whereas the switch is turned On, the same switch will appear on the Qualification and Audit Form Page when creating a New Qualification and/or Audit or when you want to edit an already existing one:
If you leave the switch Off, only Users that are part of the Group(s) you have selected in the Groups field will be available to be assigned in roles.
When turning the switch On, all Users in Scilife will be available to be assigned in the roles of the Qualification or Audit.