Your customer rating is the star rating a shipper leaves after a delivery job. Open the menu and it sits at the top next to your name, together with your other two ratings.
Your customer rating works as an average of all the ratings you have received so far. It automatically adjusts as you complete more delivery jobs and get more ratings.
Any change in your customer rating does not affect your reliability rating or your on-time rating.
A higher customer rating helps you win more of the jobs that you applied to. It does not affect which jobs you can apply to, only which jobs you'll win.
If a shipper selects you as a preferred driver, you get the highest winning chance for their jobs regardless of this rating.