I'll ensure you can assign rates specific to your client in QuickBooks Desktop for Mac, RidleyNY.

Currently, adding price rules or price levels to your customer isn't available in this version. I suggest looking for a third-party application that offers this kind of feature. 

We recommend visiting our QuickBooks Desktop Market App Store to find a versatile tool that enables you to import, export, and manipulate transactions and lists in QuickBooks Desktop.

Moreover, if you need to create a back up for your accounting data in QBDT, feel free to read this article: Back up your QuickBooks Desktop company file.

Let me know if there's anything I can do while managing your company. We'll be right here shortly.