(Note - this article is for Suppliers only).
This is very easy to do, please follow the steps below.
1. From 'Dashboard', go to [Customers] [My Customers].
2. Type the Customer's name in the 'Search for My Purchasers' field, and click on the 'blue' 'magnifying glass' icon.
3. When the Customer's name appears, click on the Purchaser Number column next to the name, and enter the new Customer number.
4. Once finished, hit 'Enter' on the keyboard, and the new Customer number will save immediately.