You can export customer and supplier transactions by completing the following process in Dimensions.
Select Debtors, Customers (ribbon menu), Sales Ledger, Records, Customers (classic/module menu) or Creditors, Suppliers (ribbon menu), Purchase Ledger, Records, Suppliers (classic/module menu)
Search for or select the relevant Customer or Supplier account.
Select the Transactions Button.
Use the enquiry screen to select relevant options
Once you have the list of transactions you need, select the Output to Excel button which is located at the top of the enquiry window.