Click Excel bar at the top which has a drop-down menu of:
•    Create New Worksheet
•    Update Existing Worksheet

Choose Create New Worksheet if you want to export your report to a new worksheet:


QB Exporting Report 2


Select appropriate self-explanatory button depending on your need.  You can also export your report to CSV file here.

Choose Update Existing Worksheet if you have a worksheet already and you want to update it with your report:


QB Exporting Report 3

You are then asked to select your workbook in the “Select workbook” box; you can click Browse bar to browse your workbook from your computer.  You can also create a CSV file by selecting appropriate button.

Additionally, in both selections above, pressing Advanced ... bar to open Advanced Excel Options, which gives you additional self-explanatory format from QuickBooks Options, Excel Options, and Print Options as shown below (default):


QB Exporting Report 4


Unless you have a specific requirement of formatting, the above default set is usually good enough.
Once you are done and click Export button, QuickBooks will automatically launch Excel and export your report to either Excel or CSV file.

Below is the exported Sales by Customer Detail report in Excel:


QB Exporting Report 5