If you are not able to add quantity, unit, and price in BUSY anymore, and it is going directly to the amount column, you can follow these steps to resolve this issue:
Step 1: Go to Administration and click on Configuration.
Step 2: Select the Voucher Series Configuration and click on Sales.
Step 3: Choose your series, such as main, and click on Voucher Configuration.
Step 4: Disable the Skip Item Quantity/Unit/Price feature.
Note: If your item unit is NA, that can be the reason for skipping Quantity, Unit, and Price.