Please learn from thins input. New Customer go to the Top; Intuit started this about 10 years ago. You notice this on Customer reports, such as AR Aging Summary or Sales by Customer Summary.
Open customer center and use View menu > Re-Sort List. You can do All Names, or just Customer. Ctl L = all names. You also can open Chart Of Accounts or Item List and fix them as well. In the List views, you might simply have clicked on a CVolumn to Sort by; Customer Center also allows you to Sort on a column, but New Customers end up at the top alpha-numerically, and only Re-Sort fixes this.
Perhaps @GarlynGay will provide a screenshot of Sorting on the Columns in a list view, to be helpful.