I'm here to provide some insight on this Customer Detail report question.
At this time, it isn't possible to add the Total as a column on any Customer Detail reports. It's designed to be at the bottom of the report as the last row since all of your customer transactions would be recorded in columns.
That being said, do you mind filling me in on what type of Customer Detail Report you pulled up? I'm determined to figure this out for you, and any additional information you can provide will help to ensure a timely solution.
Please let me know how I can help you succeed. Thanks for reaching out, I look forward to hearing from you again.