For some countries, a switch is enabled at Settings - Document Settings - Estimate name, where you can simply select Quote. When creating a new document the new document name appears.
Navigate to Settings – Document settings and choose Custom labels
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