A video will be forthcoming, but once the "Modern" calendar view is activated, calls can be moved on the calendar via drag and drop.
"Left click" with the mouse to select the appointment and then simply drag it to the desired spot. Please make sure not to click on either the customer name or service call type hyperlinks otherwise you will be routed to those respective pages.
When you are dragging the appointment, you will see the appointment box along with its shadow - a grey blank box. It is the grey box that you need to move to the correct spot on the calendar - see the screen shots below.
In addition, you can drag from the Open Call list to the main calendar.
Drag and Drop Video
Example of Drag and Drop on Calendar