When you design a report in report Designer you can generate the xml template and edit the format of the report. The editing of templates in version 8.16. and above has a bug.
Below example displays the work around for editing of the generated xml templates.

Published the report to XML Templates

Select Change and select Generate a template for ALLEMP and select Save template for customisation.

The XML Templates are generated in the XML Template folder for customisation and editing. The defualt format for the xml tempalte when originaly saved is *.xlsx. The default will work unless you make any customisations.

To make customisation to the template such as the use of conditional formatting to reformat the dates and make other changes specially for the reports and GLI files that have different formats for example dates (see below formula). This will not work with xlsx option.

The Work around

Go to the XML Template folder and open the desired template in our example it is ALLEMPtemplate and open the template.

Select “Save As” and select xls format.

Select Continue.

Go to report designer and publish the report using the xls format.

Select Using a Spreadsheet template and select Change fields highlighted above.
Select choose a template ALLEMP and choose xls format, this will pick up the template automatically. Publish the report to the new format.

Go to the generated template and make changes as required. In the example below I am changing the date format. I am also using Conditional Formatting to highlight duplicated cells. Select File and Save.

Re-run the report and export to the template.

The report will highlight the duplicate entries in column A and B as per our conditional formatting and reformat the date from column C in column D to show the date as Month/Year format when exported from chris21.