For selected countries, a switch is enabled at ⚙️ Settings - Template design and settings - Estimate settings, where you can select Quote or Estimate. When creating a new document the new document name appears on the PDF file.
Select a language if necessary and change the name from Estimate to Quote or Quotation
Change also the label Estimate No. to Quote No. or Quotation No.
Go back and Save the Settings
note: This change happens instantly to all documents