To assign default pricelist to the vendor, please follow the steps mentioned below,
Step 1: Please go to “Parties” >> vendor >> Click on the vendor you want to assign pricelist for.
Step 2: Click on edit icon.
Step 3: Scroll down and click on "Vendor Preferences.”
Step 4: Click on “Select Price list” dropdown box.
Step 5: Select the desired pricelist and click on “Update Vendor”
Pricelist will be automatically selected while creating the document for the customer.