In order to modify your RFQ answer, the quotation must be on time, with status In Progress, and be the closed envelope type. After answering, locate the desired quotation then click on its title.
After opening the quotation page, go to the Cycle panel and click on the Edit button at the bottom of the panel.
Then all fields will be enabled for editing. Make the desired change and click Post so your changes can be saved.
Changes will be logged within the Change History panel.