Significance of "Change"->"unchanged" and "New" -> "Old" statuses during maintain authorization?

Hi all, I am new in SAP Security/GRC and I need help: What does it mean to see the statuses "changed" and "New" on the 'maintain Authorization' page ? I learnt there are actions one must perform to change the 'Change' status into "unchanged' and also integrate the "New" transactions with the "old". Could anyone explain please?

Thanks