Hi Pam,
In the short term one quick trick that might be helpful is to create a set of formula fields that are set to be equal to your manual entry date fields and base your calendar off of them. This way your users still use the manual entry field for all editing in forms and reports but specifically the calendar is set to draw from the formula field. Calendar's set to formula fields can't be drag and dropped but any time someone updates the date via the record it will immediately update the formula your calendar is based off of. This way you get a calendar that can't be dragged today.
For the future and wanting to request an option on calendar reports to specifically prevent drag and drop you would want to put that up on our User Voice. The Quick Base User Voice page is a tool our Product Development team uses to track user requests for features and enhancements. The Quick Base User voice can most easily be accessed from the My Apps page in Quick Base by clicking on the orange Feedback tab that appears on the right of the page or at
http://quickbase.uservoice.com by signing in with your Quick Base credentials. This way your feedback can get passed along and others users can vote to show their support. I also usually recommend if a user makes a User Voice request to link it here in Community to that others with the same need can add their vote as well. Thank you for your time today and I hope this information is helpful.