Double Booking Issue

My biggest issue is once I enter a client in the system, send the proposal, and then retainer is paid and updated.  That client does not show up in the calendar unless I click details and enter the date and time.  Why is this section in another location.  I have overlooked this button so many time.  I feel that it should be part of the main invoice and once the retainer is marked as paid it should ask to fill in the date and time of event.  I have double booked and had heart attacks because my calendar will show I have no event….but my written paperwork will say that I do...and it’s all due to the details tab not being updated. I just lost a entire event due to this issue and had to find them another venue.