The account owner is always 'Parent 1' in the 'Parenting Time Distribution' pie chart. Time not claimed (recorded) is assigned to 'Parent 2'.
The labels 'Parent 1' and 'Parent 2' were picked to avoid using the term 'custodial' and 'non-custodial', because this may be inaccurate depending on your situation. Both custodial and non-custodial parents use OPTIMAL, and in some cases custody may not have been legally decided yet.