Having a lookup suggest the most recent records is a cool little feature, but it may not always be useful. This feature does not obey any filtered lookup conditions you may have configured. This can result in items being displayed that a user should not be allowed to select. I’m not sure if this is a bug or just an oversight.
What can we do about it?
It is possible to disable this feature. Simply navigate to the form editor and open the lookup field’s properties dialog. Under the Field Behaviour section, check the Disable most recently used items for this field option and click OK. Save and publish the form.
When setting focus to the lookup you will notice that it no longer suggests the most recently used records.