Thank you for reaching out in the Community. Allow me to help share some insight about the dialog box you're getting when sending a quote from QuickBooks Online.
If you make any changes in the quotes and estimates, QuickBooks saves them before sending to help protect your business and keep your company data secure. It also provides you the option to use this information for one-time or store it for future transactions. Currently, turning off this feature is unavailable.
I've attached some articles for additional reference while working with QuickBooks: